The superior mesenteric lymph nodes are responsible for draining the duodenum, which is the second section of the gastrointestinal system. This lymphatic drainage is important for staging gastrointestinal cancers, and is similar to the blood supply of the gut. While the coeliac lymph nodes drain the first part of the gastrointestinal system, the inferior mesenteric lymph nodes drain the third part, and the internal iliac lymph nodes drain the lower part of the rectum and some of the anal canal. The para-aortic lymph nodes are not involved in the drainage of the gastrointestinal system, but instead drain the genito-urinary system. It is important to understand the correct lymphatic drainage patterns for accurate cancer staging.

Lymphatic drainage is the process by which lymphatic vessels carry lymph, a clear fluid containing white blood cells, away from tissues and organs and towards lymph nodes. The lymphatic vessels that drain the skin and follow venous drainage are called superficial lymphatic vessels, while those that drain internal organs and structures follow the arteries and are called deep lymphatic vessels. These vessels eventually lead to lymph nodes, which filter and remove harmful substances from the lymph before it is returned to the bloodstream.

The lymphatic system is divided into two main ducts: the right lymphatic duct and the thoracic duct. The right lymphatic duct drains the right side of the head and right arm, while the thoracic duct drains everything else. Both ducts eventually drain into the venous system.

Different areas of the body have specific primary lymph node drainage sites. For example, the superficial inguinal lymph nodes drain the anal canal below the pectinate line, perineum, skin of the thigh, penis, scrotum, and vagina. The deep inguinal lymph nodes drain the glans penis, while the para-aortic lymph nodes drain the testes, ovaries, kidney, and adrenal gland. The axillary lymph nodes drain the lateral breast and upper limb, while the internal iliac lymph nodes drain the anal canal above the pectinate line, lower part of the rectum, and pelvic structures including the cervix and inferior part of the uterus. The superior mesenteric lymph nodes drain the duodenum and jejunum, while the inferior mesenteric lymph nodes drain the descending colon, sigmoid colon, and upper part of the rectum. Finally, the coeliac lymph nodes drain the stomach.

Docetaxel, a taxane chemotherapy agent, works by reducing the amount of free tubulin through the prevention of microtubule depolymerisation and disassembly during the metaphase stage of cell division, ultimately hindering mitosis.

Cytotoxic agents are drugs that are used to kill cancer cells. There are several types of cytotoxic agents, each with their own mechanism of action and potential adverse effects. Alkylating agents, such as cyclophosphamide, work by causing cross-linking in DNA. However, they can also cause haemorrhagic cystitis, myelosuppression, and transitional cell carcinoma. Cytotoxic antibiotics, like bleomycin and anthracyclines, degrade preformed DNA and stabilize DNA-topoisomerase II complex, respectively. However, they can also cause lung fibrosis and cardiomyopathy. Antimetabolites, such as methotrexate and fluorouracil, inhibit dihydrofolate reductase and thymidylate synthesis, respectively. However, they can also cause myelosuppression, mucositis, and liver or lung fibrosis. Drugs that act on microtubules, like vincristine and docetaxel, inhibit the formation of microtubules and prevent microtubule depolymerisation & disassembly, respectively. However, they can also cause peripheral neuropathy, myelosuppression, and paralytic ileus. Topoisomerase inhibitors, like irinotecan, inhibit topoisomerase I, which prevents relaxation of supercoiled DNA. However, they can also cause myelosuppression. Other cytotoxic drugs, such as cisplatin and hydroxyurea, cause cross-linking in DNA and inhibit ribonucleotide reductase, respectively. However, they can also cause ototoxicity, peripheral neuropathy, hypomagnesaemia, and myelosuppression.

Antiphospholipid syndrome is a condition where the body’s immune system produces antibodies that cause blood clots and pregnancy-related complications. The diagnosis requires one clinical event and two positive blood tests spaced at least 3 months apart. The antibodies associated with this syndrome are lupus anticoagulant, anti-cardiolipin, and anti-β2-glycoprotein. Antiphospholipid syndrome can be primary or secondary, with the latter occurring in conjunction with other autoimmune diseases. In severe cases, the condition can lead to organ failure, known as catastrophic antiphospholipid syndrome. Treatment typically involves anticoagulant medication such as heparin, while warfarin is avoided during pregnancy due to its teratogenic effects.

Hypercoagulability is a condition where the blood has an increased tendency to clot. There are several types of thrombophilia, each with their own unique features. Antithrombin deficiency is a rare genetic defect that increases the risk of thrombotic events by 10 times. Heparin may not be effective in treating this condition as it works via antithrombin. Protein C and S deficiency, which accounts for up to 5% of thrombotic episodes, occurs when there is a lack of natural anticoagulants that are produced by the liver. Factor V Leiden is the most common genetic defect accounting for deep vein thrombosis (DVT) and may account for up to 20% or more of thrombotic episodes. Antiphospholipid syndrome is a multi-organ disease that can involve pregnancy and cause both arterial and venous thrombosis. It is characterized by either Lupus anticoagulant or Anti cardiolipin antibodies, and requires anticoagulation with an INR between 3 and 4.

In summary, hypercoagulability is a condition where the blood has an increased tendency to clot. There are several types of thrombophilia, each with their own unique features. Antithrombin deficiency, protein C and S deficiency, factor V Leiden, and antiphospholipid syndrome are some of the most common types of thrombophilia. It is important to identify and treat these conditions to prevent thrombotic events.

Macrophages are still the most frequent cell type that can generate giant cells, despite the possibility of other cell types doing so.

Giant cells are masses that result from the fusion of various types of cells. Typically, these masses are composed of macrophages. It is important to note that giant cells are not the same as granulomas, although the agents that cause them may be similar. In fact, giant cells are often a reaction to foreign materials, such as suture material, and can be seen in histological sections stained with haematoxylin and eosin. Overall, giant cells are a unique phenomenon in cellular biology that can provide insight into the body’s response to foreign substances.

JAK2 Mutation and Primary Polycythaemia

Polycythaemia is a condition characterized by an increase in the number of red blood cells in the body. In primary polycythaemia, over 95% of cases are associated with a mutation in the JAK2 pathway. This mutation causes the pathway to be constantly active, leading to the production of red blood cells even in the absence of erythropoietin (EPO). The most common mutation occurs in exon 12, affecting position V617F.

On the other hand, secondary causes of polycythaemia include COPD and smoking, which lower blood oxygenation and trigger the secretion of EPO by the kidney’s peritubular cells. ADPKD also promotes the secretion of increased EPO, resulting in the production and release of more red blood cells. Dehydration, on the other hand, reduces plasma volume, leading to an apparent/relative polycythaemia. While these factors can cause an increase in red blood cells, they are not associated with a primary haematological disorder like the JAK2 mutation.

If DNA cannot be repaired, it triggers cellular apoptosis instead of necrosis.

Genetic Conditions and Their Association with Surgical Diseases

Li-Fraumeni Syndrome is an autosomal dominant genetic condition caused by mutations in the p53 tumour suppressor gene. Individuals with this syndrome have a high incidence of malignancies, particularly sarcomas and leukaemias. The diagnosis is made when an individual develops sarcoma under the age of 45 or when a first-degree relative is diagnosed with any cancer below the age of 45 and another family member develops malignancy under the age of 45 or sarcoma at any age.

BRCA 1 and 2 are genetic conditions carried on chromosome 17 and chromosome 13, respectively. These conditions are linked to developing breast cancer with a 60% risk and an associated risk of developing ovarian cancer with a 55% risk for BRCA 1 and 25% risk for BRCA 2. BRCA2 mutation is also associated with prostate cancer in men.

Lynch Syndrome is another autosomal dominant genetic condition that causes individuals to develop colonic cancer and endometrial cancer at a young age. 80% of affected individuals will get colonic and/or endometrial cancer. High-risk individuals may be identified using the Amsterdam criteria, which include three or more family members with a confirmed diagnosis of colorectal cancer, two successive affected generations, and one or more colon cancers diagnosed under the age of 50 years.

Gardners syndrome is an autosomal dominant familial colorectal polyposis that causes multiple colonic polyps. Extra colonic diseases include skull osteoma, thyroid cancer, and epidermoid cysts. Desmoid tumours are seen in 15% of individuals with this syndrome. Due to colonic polyps, most patients will undergo colectomy to reduce the risk of colorectal cancer. It is now considered a variant of familial adenomatous polyposis coli.

Overall, these genetic conditions have a significant association with surgical diseases, and early identification and management can help reduce the risk of malignancies and other associated conditions.

Vitamin deficiency may occur after an ileocaecal resection.

Vitamin B12 is essential for the development of red blood cells and the maintenance of the nervous system. It is absorbed through the binding of intrinsic factor, which is secreted by parietal cells in the stomach, and actively absorbed in the terminal ileum. A deficiency in vitamin B12 can be caused by pernicious anaemia, post gastrectomy, a vegan or poor diet, disorders or surgery of the terminal ileum, Crohn’s disease, or metformin use.

Symptoms of vitamin B12 deficiency include macrocytic anaemia, a sore tongue and mouth, neurological symptoms, and neuropsychiatric symptoms such as mood disturbances. The dorsal column is usually affected first, leading to joint position and vibration issues before distal paraesthesia.

Management of vitamin B12 deficiency involves administering 1 mg of IM hydroxocobalamin three times a week for two weeks, followed by once every three months if there is no neurological involvement. If a patient is also deficient in folic acid, it is important to treat the B12 deficiency first to avoid subacute combined degeneration of the cord.

Plasma cells would be visible in a bone marrow aspirate to diagnose multiple myeloma, which is characterized by osteolytic lesions, decreased renal function, bony pain, and the presence of Bence-Jones proteins. This condition is a type of B-cell neoplasm affecting plasma cells.

Understanding Multiple Myeloma: Features and Investigations

Multiple myeloma is a type of cancer that affects the plasma cells in the bone marrow. It is most commonly found in patients aged 60-70 years. The disease is characterized by a range of symptoms, which can be remembered using the mnemonic CRABBI. These include hypercalcemia, renal damage, anemia, bleeding, bone lesions, and increased susceptibility to infection. Other features of multiple myeloma include amyloidosis, carpal tunnel syndrome, neuropathy, and hyperviscosity.

To diagnose multiple myeloma, a range of investigations are required. Blood tests can reveal anemia, renal failure, and hypercalcemia. Protein electrophoresis can detect raised levels of monoclonal IgA/IgG proteins in the serum, while bone marrow aspiration can confirm the diagnosis if the number of plasma cells is significantly raised. Imaging studies, such as whole-body MRI or X-rays, can be used to detect osteolytic lesions.

The diagnostic criteria for multiple myeloma require one major and one minor criteria or three minor criteria in an individual who has signs or symptoms of the disease. Major criteria include the presence of plasmacytoma, 30% plasma cells in a bone marrow sample, or elevated levels of M protein in the blood or urine. Minor criteria include 10% to 30% plasma cells in a bone marrow sample, minor elevations in the level of M protein in the blood or urine, osteolytic lesions, or low levels of antibodies in the blood. Understanding the features and investigations of multiple myeloma is crucial for early detection and effective treatment.

Understanding Antithrombin III Deficiency

Antithrombin III deficiency is a genetic condition that affects approximately 1 in 3,000 people. It is inherited in an autosomal dominant manner. This condition occurs when the body does not produce enough antithrombin III, a protein that helps to prevent blood clots by inhibiting certain clotting factors. Some patients with this deficiency have a shortage of normal antithrombin III, while others produce abnormal antithrombin III.

People with antithrombin III deficiency are at an increased risk of developing recurrent venous thromboses, which are blood clots that form in the veins. While arterial thromboses can also occur, they are less common. To manage this condition, patients may need to take warfarin for the rest of their lives to prevent thromboembolic events. During pregnancy, heparin may be used instead. Antithrombin III concentrates may also be used during surgery or childbirth.

It is important to note that patients with antithrombin III deficiency have a degree of resistance to heparin, so anti-Xa levels should be monitored carefully to ensure adequate anticoagulation. Compared to other inherited thrombophilias, antithrombin III deficiency is less common but has a higher relative risk of venous thromboembolism. Understanding this condition and its management is crucial for those affected and their healthcare providers.

The Factor V Leiden mutation causes activated protein C resistance, resulting in excess clotting due to inefficient inactivation of factor V. This is the correct answer.

Antiphospholipid antibodies binding to plasma membranes is not the correct answer as it is a mechanism of blood clot formation in antiphospholipid syndrome (APS).

High levels of platelets in the blood is also not the correct answer as it is not implicated in Factor V Leiden. Thrombocytosis, or high levels of platelets, can lead to clots but is not related to this mutation.

Low levels of factor V in the blood is also not the correct answer as factor V deficiency is a rare inherited bleeding disorder, not a clotting disorder. It is a form of haemophilia.

Understanding Factor V Leiden

Factor V Leiden is a common inherited thrombophilia, affecting around 5% of the UK population. It is caused by a mutation in the Factor V Leiden protein, resulting in activated factor V being inactivated 10 times more slowly by activated protein C than normal. This leads to activated protein C resistance, which increases the risk of venous thrombosis. Heterozygotes have a 4-5 fold risk of venous thrombosis, while homozygotes have a 10 fold risk, although the prevalence of homozygotes is much lower at 0.05%.

Despite its prevalence, screening for Factor V Leiden is not recommended, even after a venous thromboembolism. This is because a previous thromboembolism itself is a risk factor for further events, and specific management should be based on this rather than the particular thrombophilia identified.

Other inherited thrombophilias include Prothrombin gene mutation, Protein C deficiency, Protein S deficiency, and Antithrombin III deficiency. The table below shows the prevalence and relative risk of venous thromboembolism for each of these conditions.

Overall, understanding Factor V Leiden and other inherited thrombophilias can help healthcare professionals identify individuals at higher risk of venous thrombosis and provide appropriate management to prevent future events.

Condition | Prevalence | Relative risk of VTE
— | — | —
Factor V Leiden (heterozygous) | 5% | 4
Factor V Leiden (homozygous) | 0.05% | 10
Prothrombin gene mutation (heterozygous) | 1.5% | 3
Protein C deficiency | 0.3% | 10
Protein S deficiency | 0.1% | 5-10
Antithrombin III deficiency | 0.02% | 10-20

Tranexamic acid prevents major haemorrhage by binding to plasminogen and preventing plasmin from breaking down fibrin clots. Its mechanism of action is not related to increasing the availability of vitamin K or inhibiting anticlotting factors protein C and S. Similarly, reducing the availability of vitamin K would not be the mechanism of action of tranexamic acid. While stimulating anticlotting factors protein C and S would maintain clots, it is not the mechanism of action of tranexamic acid.

Understanding Tranexamic Acid

Tranexamic acid is a synthetic derivative of lysine that acts as an antifibrinolytic. Its primary function is to bind to lysine receptor sites on plasminogen or plasmin, preventing plasmin from degrading fibrin. This medication is commonly prescribed to treat menorrhagia.

In addition to its use in treating menorrhagia, tranexamic acid has been investigated for its role in trauma. The CRASH 2 trial found that administering tranexamic acid within the first 3 hours of bleeding trauma can be beneficial. In cases of major haemorrhage, tranexamic acid is given as an IV bolus followed by an infusion.

Ongoing research is also exploring the potential of tranexamic acid in treating traumatic brain injury. Overall, tranexamic acid is a medication with important applications in managing bleeding disorders and trauma.

Hodgkin’s disease is characterized by the presence of Reed Sternberg cells, while sarcoid is associated with the presence of all other cell types.

Chronic inflammation can occur as a result of acute inflammation or as a primary process. There are three main processes that can lead to chronic inflammation: persisting infection with certain organisms, prolonged exposure to non-biodegradable substances, and autoimmune conditions involving antibodies formed against host antigens. Acute inflammation involves changes to existing vascular structure and increased permeability of endothelial cells, as well as infiltration of neutrophils. In contrast, chronic inflammation is characterized by angiogenesis and the predominance of macrophages, plasma cells, and lymphocytes. The process may resolve with suppuration, complete resolution, abscess formation, or progression to chronic inflammation. Healing by fibrosis is the main result of chronic inflammation. Granulomas, which consist of a microscopic aggregation of macrophages, are pathognomonic of chronic inflammation and can be found in conditions such as colonic Crohn’s disease. Growth factors released by activated macrophages, such as interferon and fibroblast growth factor, may have systemic features resulting in systemic symptoms and signs in individuals with long-standing chronic inflammation.

Down’s Syndrome and Associated Conditions

Down’s syndrome, also known as trisomy 21, is characterized by several physical features such as a wide, flat nasal bridge, macroglossia, and clinodactyly. Other common features include a round face, hypothyroidism, a sandal gap between the toes, and a single palmar crease. Individuals with Down’s syndrome are predisposed to certain conditions such as Alzheimer’s disease and acute leukaemias. However, nephroblastomas, primary bone malignancies, soft tissue tumours, and solid CNS tumours are not directly related to Down’s syndrome. Nephroblastomas are associated with an absent iris, while primary bone malignancies have few predisposing factors except for rare cancer syndromes. Soft tissue tumours, such as rhabdomyosarcomas, are linked to familial retinoblastoma, while solid CNS tumours are increased in cancer syndromes like Li-Fraumeni. the associated conditions of Down’s syndrome can aid in early detection and treatment of these conditions.

Irinotecan prevents relaxation of supercoiled DNA by inhibiting topoisomerase I, an enzyme that regulates DNA supercoiling during mitosis and meiosis. Other topoisomerase inhibitors include topotecan, etoposide, and teniposide.

Azathioprine is a purine analogue that inhibits DNA polymerase, thereby halting DNA synthesis.

5-fluorouracil is a pyrimidine antagonist that inhibits thymidylate synthase, leading to a reduction in pyrimidine nucleotides.

Tyrosine kinase inhibitors like imatinib and erlotinib have significantly improved the prognosis for patients with chronic myeloid leukemia (CML).

Cytotoxic agents are drugs that are used to kill cancer cells. There are several types of cytotoxic agents, each with their own mechanism of action and potential adverse effects. Alkylating agents, such as cyclophosphamide, work by causing cross-linking in DNA. However, they can also cause haemorrhagic cystitis, myelosuppression, and transitional cell carcinoma. Cytotoxic antibiotics, like bleomycin and anthracyclines, degrade preformed DNA and stabilize DNA-topoisomerase II complex, respectively. However, they can also cause lung fibrosis and cardiomyopathy. Antimetabolites, such as methotrexate and fluorouracil, inhibit dihydrofolate reductase and thymidylate synthesis, respectively. However, they can also cause myelosuppression, mucositis, and liver or lung fibrosis. Drugs that act on microtubules, like vincristine and docetaxel, inhibit the formation of microtubules and prevent microtubule depolymerisation & disassembly, respectively. However, they can also cause peripheral neuropathy, myelosuppression, and paralytic ileus. Topoisomerase inhibitors, like irinotecan, inhibit topoisomerase I, which prevents relaxation of supercoiled DNA. However, they can also cause myelosuppression. Other cytotoxic drugs, such as cisplatin and hydroxyurea, cause cross-linking in DNA and inhibit ribonucleotide reductase, respectively. However, they can also cause ototoxicity, peripheral neuropathy, hypomagnesaemia, and myelosuppression.

Rivaroxaban is a direct inhibitor of factor Xa, which is the correct answer. Pulmonary emboli can be caused by various factors, and symptoms include chest pain, dyspnoea, and haemoptysis. Factor Xa inhibitors, such as rivaroxaban, have replaced warfarin as the first-line treatment for stroke prevention in patients with atrial fibrillation.

Dabigatran is a direct thrombin inhibitor and has a different mechanism of action compared to rivaroxaban. It is commonly used for venous thromboembolism prophylaxis after total knee or hip replacement surgery.

Dalteparin is a type of low molecular weight heparin (LMWH) and has a different mechanism of action compared to factor Xa inhibitors. It is used for prophylaxis against venous thromboembolism in patients who are immobile or have recently had surgery.

Fondaparinux is an indirect inhibitor of factor Xa and is not the correct answer. It is used for the treatment of deep-vein thrombosis, pulmonary embolism, and acute coronary syndrome.

Direct oral anticoagulants (DOACs) are medications used to prevent stroke in non-valvular atrial fibrillation (AF), as well as for the prevention and treatment of venous thromboembolism (VTE). To be prescribed DOACs for stroke prevention, patients must have certain risk factors, such as a prior stroke or transient ischaemic attack, age 75 or older, hypertension, diabetes mellitus, or heart failure. There are four DOACs available, each with a different mechanism of action and method of excretion. Dabigatran is a direct thrombin inhibitor, while rivaroxaban, apixaban, and edoxaban are direct factor Xa inhibitors. The majority of DOACs are excreted either through the kidneys or the liver, with the exception of apixaban and edoxaban, which are excreted through the feces. Reversal agents are available for dabigatran and rivaroxaban, but not for apixaban or edoxaban.

Cytarabine is a medication used in chemotherapy to treat acute myeloid leukaemia (AML). It works by interfering with DNA synthesis during the S-phase of the cell cycle and inhibiting DNA polymerase.

Allopurinol is a medication that inhibits xanthine oxidase, which prevents the production of uric acid. It is commonly used to treat gout, but can also be used to prevent hyperuricaemia in high-grade lymphoma and leukaemia before chemotherapy treatment.

Methotrexate works by inhibiting dihydrofolate reductase and thymidylate synthesis. It is used to treat rheumatoid arthritis and various types of cancer.

Ondansetron is an anti-emetic medication that is used to prevent nausea during chemotherapy treatment. It works by selectively blocking serotonin receptors (5-HT3) in the chemoreceptor trigger zone (CTZ) of the medulla.

Cytotoxic agents are drugs that are used to kill cancer cells. There are several types of cytotoxic agents, each with their own mechanism of action and potential adverse effects. Alkylating agents, such as cyclophosphamide, work by causing cross-linking in DNA. However, they can also cause haemorrhagic cystitis, myelosuppression, and transitional cell carcinoma. Cytotoxic antibiotics, like bleomycin and anthracyclines, degrade preformed DNA and stabilize DNA-topoisomerase II complex, respectively. However, they can also cause lung fibrosis and cardiomyopathy. Antimetabolites, such as methotrexate and fluorouracil, inhibit dihydrofolate reductase and thymidylate synthesis, respectively. However, they can also cause myelosuppression, mucositis, and liver or lung fibrosis. Drugs that act on microtubules, like vincristine and docetaxel, inhibit the formation of microtubules and prevent microtubule depolymerisation & disassembly, respectively. However, they can also cause peripheral neuropathy, myelosuppression, and paralytic ileus. Topoisomerase inhibitors, like irinotecan, inhibit topoisomerase I, which prevents relaxation of supercoiled DNA. However, they can also cause myelosuppression. Other cytotoxic drugs, such as cisplatin and hydroxyurea, cause cross-linking in DNA and inhibit ribonucleotide reductase, respectively. However, they can also cause ototoxicity, peripheral neuropathy, hypomagnesaemia, and myelosuppression.

Apixaban directly inhibits factor Xa, while bivalirudin and dabigatran directly inhibit thrombin. On the other hand, enoxaparin is a type of low molecular weight heparin that indirectly inhibits factor Xa by forming a complex with antithrombin III, leading to irreversible inactivation of factor Xa.

Direct oral anticoagulants (DOACs) are medications used to prevent stroke in non-valvular atrial fibrillation (AF), as well as for the prevention and treatment of venous thromboembolism (VTE). To be prescribed DOACs for stroke prevention, patients must have certain risk factors, such as a prior stroke or transient ischaemic attack, age 75 or older, hypertension, diabetes mellitus, or heart failure. There are four DOACs available, each with a different mechanism of action and method of excretion. Dabigatran is a direct thrombin inhibitor, while rivaroxaban, apixaban, and edoxaban are direct factor Xa inhibitors. The majority of DOACs are excreted either through the kidneys or the liver, with the exception of apixaban and edoxaban, which are excreted through the feces. Reversal agents are available for dabigatran and rivaroxaban, but not for apixaban or edoxaban.

Invasion is a characteristic of invasive disease and is not typically seen in cases of DCIS. However, angiogenesis may be present in cases of high grade DCIS.

Characteristics of Malignancy in Histopathology

Histopathology is the study of tissue architecture and cellular changes in disease. In malignancy, there are several distinct characteristics that differentiate it from normal tissue or benign tumors. These features include abnormal tissue architecture, coarse chromatin, invasion of the basement membrane, abnormal mitoses, angiogenesis, de-differentiation, areas of necrosis, and nuclear pleomorphism.

Abnormal tissue architecture refers to the disorganized and irregular arrangement of cells within the tissue. Coarse chromatin refers to the appearance of the genetic material within the nucleus, which appears clumped and irregular. Invasion of the basement membrane is a hallmark of invasive malignancy, as it indicates that the cancer cells have broken through the protective layer that separates the tissue from surrounding structures. Abnormal mitoses refer to the process of cell division, which is often disrupted in cancer cells. Angiogenesis is the process by which new blood vessels are formed, which is necessary for the growth and spread of cancer cells. De-differentiation refers to the loss of specialized functions and characteristics of cells, which is common in cancer cells. Areas of necrosis refer to the death of tissue due to lack of blood supply or other factors. Finally, nuclear pleomorphism refers to the variability in size and shape of the nuclei within cancer cells.

Overall, these characteristics are important for the diagnosis and treatment of malignancy, as they help to distinguish cancer cells from normal tissue and benign tumors. By identifying these features in histopathology samples, doctors can make more accurate diagnoses and develop more effective treatment plans for patients with cancer.

Vincristine inhibits the formation of microtubules, which are essential for separating chromosomes during cell division. This mechanism is also shared by paclitaxel, a member of the taxane family. Alkylating agents, such as cyclophosphamide, disrupt the double helix of DNA by adding an alkyl group to guanine bases. Methotrexate inhibits dihydrofolate reductase, an enzyme that supports folate in DNA synthesis. Pyrimidine antagonists, like cytarabine, prevent the use of pyrimidines in DNA synthesis.

Cytotoxic agents are drugs that are used to kill cancer cells. There are several types of cytotoxic agents, each with their own mechanism of action and potential adverse effects. Alkylating agents, such as cyclophosphamide, work by causing cross-linking in DNA. However, they can also cause haemorrhagic cystitis, myelosuppression, and transitional cell carcinoma. Cytotoxic antibiotics, like bleomycin and anthracyclines, degrade preformed DNA and stabilize DNA-topoisomerase II complex, respectively. However, they can also cause lung fibrosis and cardiomyopathy. Antimetabolites, such as methotrexate and fluorouracil, inhibit dihydrofolate reductase and thymidylate synthesis, respectively. However, they can also cause myelosuppression, mucositis, and liver or lung fibrosis. Drugs that act on microtubules, like vincristine and docetaxel, inhibit the formation of microtubules and prevent microtubule depolymerisation & disassembly, respectively. However, they can also cause peripheral neuropathy, myelosuppression, and paralytic ileus. Topoisomerase inhibitors, like irinotecan, inhibit topoisomerase I, which prevents relaxation of supercoiled DNA. However, they can also cause myelosuppression. Other cytotoxic drugs, such as cisplatin and hydroxyurea, cause cross-linking in DNA and inhibit ribonucleotide reductase, respectively. However, they can also cause ototoxicity, peripheral neuropathy, hypomagnesaemia, and myelosuppression.

The clotting cascade is an example of a positive feedback mechanism, where the presence of clotting factors attracts further clotting factors until a functioning clot is formed. On the other hand, blood sugar, blood pressure, and cortisol are controlled via negative feedback mechanisms. When blood sugar rises, insulin is released to transport glucose into cells, lowering blood sugar. When BP is low, the RAAS is activated to increase BP through vasoconstriction and retention of salt and water. Cortisol is released in response to ACTH, which is inhibited by high levels of cortisol through negative feedback on the hypothalamus and anterior pituitary.

The Coagulation Cascade: Two Pathways to Fibrin Formation

The coagulation cascade is a complex process that leads to the formation of a blood clot. There are two pathways that can lead to fibrin formation: the intrinsic pathway and the extrinsic pathway. The intrinsic pathway involves components that are already present in the blood and has a minor role in clotting. It is initiated by subendothelial damage, such as collagen, which leads to the formation of the primary complex on collagen by high-molecular-weight kininogen (HMWK), prekallikrein, and Factor 12. This complex activates Factor 11, which in turn activates Factor 9. Factor 9, along with its co-factor Factor 8a, forms the tenase complex, which activates Factor 10.

The extrinsic pathway, on the other hand, requires tissue factor released by damaged tissue. This pathway is initiated by tissue damage, which leads to the binding of Factor 7 to tissue factor. This complex activates Factor 9, which works with Factor 8 to activate Factor 10. Both pathways converge at the common pathway, where activated Factor 10 causes the conversion of prothrombin to thrombin. Thrombin hydrolyses fibrinogen peptide bonds to form fibrin and also activates factor 8 to form links between fibrin molecules.

Finally, fibrinolysis occurs, which is the process of clot resorption. Plasminogen is converted to plasmin to facilitate this process. It is important to note that certain factors are involved in both pathways, such as Factor 10, and that some factors are vitamin K dependent, such as Factors 2, 7, 9, and 10. The intrinsic pathway can be assessed by measuring the activated partial thromboplastin time (APTT), while the extrinsic pathway can be assessed by measuring the prothrombin time (PT).

If Howell-Jolly bodies are present in the peripheral smear of a sickle cell anemia patient, it indicates that they have undergone autosplenectomy. Sickle cell disease can lead to various complications, including vaso-occlusive crisis, parvovirus B19 infections, splenic sequestration, and eventually, autosplenectomy. However, based on the absence of symptoms and other factors, vaso-occlusive crisis, parvovirus B19 infection, and splenic sequestration are unlikely causes in this case.

Pathological Red Cell Forms in Blood Films

Blood films are used to examine the morphology of red blood cells and identify any abnormalities. Pathological red cell forms are associated with various conditions and can provide important diagnostic information. Some of the common pathological red cell forms include target cells, tear-drop poikilocytes, spherocytes, basophilic stippling, Howell-Jolly bodies, Heinz bodies, schistocytes, pencil poikilocytes, burr cells (echinocytes), and acanthocytes.

Target cells are seen in conditions such as sickle-cell/thalassaemia, iron-deficiency anaemia, hyposplenism, and liver disease. Tear-drop poikilocytes are associated with myelofibrosis, while spherocytes are seen in hereditary spherocytosis and autoimmune hemolytic anaemia. Basophilic stippling is a characteristic feature of lead poisoning, thalassaemia, sideroblastic anaemia, and myelodysplasia. Howell-Jolly bodies are seen in hyposplenism, while Heinz bodies are associated with G6PD deficiency and alpha-thalassaemia. Schistocytes or ‘helmet cells’ are seen in conditions such as intravascular haemolysis, mechanical heart valve, and disseminated intravascular coagulation. Pencil poikilocytes are seen in iron deficiency anaemia, while burr cells (echinocytes) are associated with uraemia and pyruvate kinase deficiency. Acanthocytes are seen in abetalipoproteinemia.

In addition to these red cell forms, hypersegmented neutrophils are seen in megaloblastic anaemia. Identifying these pathological red cell forms in blood films can aid in the diagnosis and management of various conditions.

DIC, also known as consumptive coagulopathy, is a condition where the coagulation cascade is overactivated, leading to unchecked bleeding. This is due to the depletion of clotting mechanisms. Normally, clot formation and breakdown are balanced, with thrombin playing a key role in both processes. In DIC, patients may have prolonged coagulation times, thrombocytopenia, high levels of fibrin degradation products, elevated D-dimer levels, and microangiopathic pathology on peripheral smears. The excess fibrin strands in the intravascular circulation cause mechanical damage to red blood cells, resulting in schistocyte formation, thrombocytopenia, and consumption of clotting factors. Bite cells are abnormally shaped red blood cells with semicircular portions removed from the cell margin, seen in G6PD deficiency. Dacrocytes are teardrop-shaped cells seen in myelofibrosis and marrow disorders, while elliptocytes are red cells varying in shape from elongated to oval, seen in various disorders.

Disseminated Intravascular Coagulation: A Condition of Simultaneous Coagulation and Haemorrhage

Disseminated intravascular coagulation (DIC) is a medical condition characterized by simultaneous coagulation and haemorrhage. It is caused by the initial formation of thrombi that consume clotting factors and platelets, ultimately leading to bleeding. DIC can be caused by various factors such as infection, malignancy, trauma, liver disease, and obstetric complications.

Clinically, bleeding is usually the dominant feature of DIC, accompanied by bruising, ischaemia, and organ failure. Blood tests can reveal prolonged clotting times, thrombocytopenia, decreased fibrinogen, and increased fibrinogen degradation products. The treatment of DIC involves addressing the underlying cause and providing supportive management.

In summary, DIC is a serious medical condition that requires prompt diagnosis and management. It is important to identify the underlying cause and provide appropriate treatment to prevent further complications. With proper care and management, patients with DIC can recover and regain their health.

A helpful mnemonic for remembering transfusion reactions is Got a bad unit. Each letter represents a potential complication:

G – Graft vs. Host disease
O – Overload
T – Thrombocytopenia
A – Alloimmunization
B – Blood pressure unstable
A – Acute hemolytic reaction
D – Delayed hemolytic reaction
U – Urticaria
N – Neutrophilia
I – Infection
T – Transfusion-associated lung injury

Graft vs. Host disease occurs when the patient’s own lymphocytes are similar to the donor’s lymphocytes, causing severe complications. Thrombocytopenia may occur a few days after transfusion and may resolve on its own. Patients with IGA antibodies require IgA deficient blood transfusions.

Blood product transfusion complications can be categorized into immunological, infective, and other complications. Immunological complications include acute haemolytic reactions, non-haemolytic febrile reactions, and allergic/anaphylaxis reactions. Infective complications may arise due to transmission of vCJD, although measures have been taken to minimize this risk. Other complications include transfusion-related acute lung injury (TRALI), transfusion-associated circulatory overload (TACO), hyperkalaemia, iron overload, and clotting.

Non-haemolytic febrile reactions are thought to be caused by antibodies reacting with white cell fragments in the blood product and cytokines that have leaked from the blood cell during storage. These reactions may occur in 1-2% of red cell transfusions and 10-30% of platelet transfusions. Minor allergic reactions may also occur due to foreign plasma proteins, while anaphylaxis may be caused by patients with IgA deficiency who have anti-IgA antibodies.

Acute haemolytic transfusion reaction is a serious complication that results from a mismatch of blood group (ABO) which causes massive intravascular haemolysis. Symptoms begin minutes after the transfusion is started and include a fever, abdominal and chest pain, agitation, and hypotension. Treatment should include immediate transfusion termination, generous fluid resuscitation with saline solution, and informing the lab. Complications include disseminated intravascular coagulation and renal failure.

TRALI is a rare but potentially fatal complication of blood transfusion that is characterized by the development of hypoxaemia/acute respiratory distress syndrome within 6 hours of transfusion. On the other hand, TACO is a relatively common reaction due to fluid overload resulting in pulmonary oedema. As well as features of pulmonary oedema, the patient may also be hypertensive, a key difference from patients with TRALI.

In coeliac disease, the spleen may undergo atrophy and Howell-Jolly bodies may be observed in red blood cells. Histiocytosis X includes Letterer-Siwe disease, which involves the excessive growth of macrophages.

The Anatomy and Function of the Spleen

The spleen is an organ located in the left upper quadrant of the abdomen. Its size can vary depending on the amount of blood it contains, but the typical adult spleen is 12.5cm long and 7.5cm wide, with a weight of 150g. The spleen is almost entirely covered by peritoneum and is separated from the 9th, 10th, and 11th ribs by both diaphragm and pleural cavity. Its shape is influenced by the state of the colon and stomach, with gastric distension causing it to resemble an orange segment and colonic distension causing it to become more tetrahedral.

The spleen has two folds of peritoneum that connect it to the posterior abdominal wall and stomach: the lienorenal ligament and gastrosplenic ligament. The lienorenal ligament contains the splenic vessels, while the short gastric and left gastroepiploic branches of the splenic artery pass through the layers of the gastrosplenic ligament. The spleen is in contact with the phrenicocolic ligament laterally.

The spleen has two main functions: filtration and immunity. It filters abnormal blood cells and foreign bodies such as bacteria, and produces properdin and tuftsin, which help target fungi and bacteria for phagocytosis. The spleen also stores 40% of platelets, reutilizes iron, and stores monocytes. Disorders of the spleen include massive splenomegaly, myelofibrosis, chronic myeloid leukemia, visceral leishmaniasis, malaria, Gaucher’s syndrome, portal hypertension, lymphoproliferative disease, haemolytic anaemia, infection, infective endocarditis, sickle-cell, thalassaemia, and rheumatoid arthritis.

Leukaemia Types and Prognosis

As with high-grade lymphomas, acute leukaemias have a higher chance of being cured than chronic leukaemias. However, chronic leukaemias such as CLL may not require treatment at the time of diagnosis and may not cause death for many years. Acute leukaemias, on the other hand, have a higher initial mortality rate.

The diagnosis of acute leukaemia can be made if the blasts account for more than 20% of the bone marrow or peripheral blood, or if there is a blast count with a recognized cytogenetic abnormality associated with AML. Gum hypertrophy is more commonly associated with AML, especially acute monocytic leukaemia.

Females generally have a better prognosis than males when it comes to acute leukaemias. ALL most commonly arises from B-lymphocyte populations, while AML arising from pre-existing conditions such as the myeloproliferative neoplasms is associated with a poorer prognosis than that arising de novo.

The submental lymph nodes are the primary site of lymphatic drainage from the tip of the tongue. The lymph will then spread to the deep cervical lymph nodes.

Lymphatic Drainage of the Tongue

The lymphatic drainage of the tongue varies depending on the location of the tumour. The anterior two-thirds of the tongue have minimal communication of lymphatics across the midline, resulting in metastasis to the ipsilateral nodes being more common. On the other hand, the posterior third of the tongue has communicating networks, leading to early bilateral nodal metastases being more common in this area.

The tip of the tongue drains to the submental nodes and then to the deep cervical nodes, while the mid portion of the tongue drains to the submandibular nodes and then to the deep cervical nodes. If mid tongue tumours are laterally located, they will usually drain to the ipsilateral deep cervical nodes. However, those from more central regions may have bilateral deep cervical nodal involvement. Understanding the lymphatic drainage of the tongue is crucial in determining the spread of tumours and planning appropriate treatment.

Doxorubicin is an anthracycline that works by stabilizing the DNA-topoisomerase II complex and inhibiting DNA and RNA synthesis. It is used to treat acute leukemias, Hodgkin’s and non-Hodgkin’s lymphoma, and some solid tumors such as breast and sarcoma. However, it can cause cardiomyopathy as a potential complication. Ondansetron is a 5-HT3 antagonist that is used to manage chemotherapy-induced nausea and vomiting. Beta-blockers like bisoprolol and atenolol, on the other hand, inhibit beta-1 receptors and are used to treat hypertension, angina, heart failure, and atrial fibrillation. They are not cytotoxic medications. Cisplatin is a cytotoxic agent that inhibits cell division by causing cross-linking of DNA. It is used to treat various cancers such as testicular, lung, cervical, bladder, head and neck, and ovarian cancer. Methotrexate, another cytotoxic agent, inhibits dihydrofolate reductase and is commonly used to treat rheumatoid arthritis. However, it can cause gastrointestinal disturbance as a side effect.

Cytotoxic agents are drugs that are used to kill cancer cells. There are several types of cytotoxic agents, each with their own mechanism of action and potential adverse effects. Alkylating agents, such as cyclophosphamide, work by causing cross-linking in DNA. However, they can also cause haemorrhagic cystitis, myelosuppression, and transitional cell carcinoma. Cytotoxic antibiotics, like bleomycin and anthracyclines, degrade preformed DNA and stabilize DNA-topoisomerase II complex, respectively. However, they can also cause lung fibrosis and cardiomyopathy. Antimetabolites, such as methotrexate and fluorouracil, inhibit dihydrofolate reductase and thymidylate synthesis, respectively. However, they can also cause myelosuppression, mucositis, and liver or lung fibrosis. Drugs that act on microtubules, like vincristine and docetaxel, inhibit the formation of microtubules and prevent microtubule depolymerisation & disassembly, respectively. However, they can also cause peripheral neuropathy, myelosuppression, and paralytic ileus. Topoisomerase inhibitors, like irinotecan, inhibit topoisomerase I, which prevents relaxation of supercoiled DNA. However, they can also cause myelosuppression. Other cytotoxic drugs, such as cisplatin and hydroxyurea, cause cross-linking in DNA and inhibit ribonucleotide reductase, respectively. However, they can also cause ototoxicity, peripheral neuropathy, hypomagnesaemia, and myelosuppression.

Acute Lymphoblastic Leukaemia

Acute lymphoblastic leukaemia (ALL) is a type of cancer that commonly affects children over the age of one. It occurs when a lymphocyte precursor, known as a ‘blast cell’, grows abnormally in the bone marrow, leading to a failure of normal blood cell production. This results in peripheral cytopenias, which can cause symptoms such as anaemia, recurrent infections, and purpura. While a raised peripheral white cell count may occur in severe or late-stage disease, it is not common.

Compared to other types of leukaemia and lymphoma, ALL is more likely to present with bone marrow failure symptoms. Acute myeloid leukaemia, for example, is more common in the elderly and presents with a raised peripheral white cell count. Burkitt lymphoma, on the other hand, is a high-grade non-Hodgkin lymphoma that typically presents with lymphadenopathy. Chronic lymphocytic leukaemia is also more common in the elderly and presents with a peripheral lymphocytosis. Langerhans histiocytosis, a condition that affects antigen-presenting cells, is more common in young children and often affects the skin or bones. While it can cause marrow failure, it is a rare occurrence.

In summary, ALL is a type of cancer that affects children and is caused by abnormal growth of blast cells in the bone marrow. It can cause symptoms of bone marrow failure, such as anaemia, recurrent infections, and purpura. While other types of leukaemia and lymphoma may present with different symptoms, ALL is more likely to present with bone marrow failure symptoms.