Gamma delta T cells are of low abundance in the body, are found in the gut mucosa, skin, lungs and uterus, and are involved in the initiation and propagation of immune responses. Their ligands are not known in detail, but the gamma delta T cell receptors recognise intact proteins rather than MHC-presented peptides. Like alpha beta T cells, they develop in the thymus.

Bombesin is a tumour marker elevated in small cell lung carcinomas, as well as in gastric carcinomas and retinoblastomas.

Tumour markers can be divided into:
1. Monoclonal antibodies
CA 125: Ovarian cancer, primary peritoneal cancer
CA 19-9: Pancreatic cancer
CA 15-3: Breast cancer

2. Tumour specific antigens
Prostate specific antigen (PSA): Prostatic carcinoma
Alpha-feto protein (AFP): Hepatocellular carcinoma, teratoma
Carcinoembryonic antigen (CEA): Colorectal cancer
S-100: Melanoma, schwannomas
Bombesin: Small cell lung carcinoma, gastric cancer

3. Enzymes
Alkaline phosphatase (ALP)
Neuron specific enolase (NSE)

4. Hormones
Calcitonin
Antidiuretic hormone (ADH)
Human chorionic gonadotropin (hCG)

Hypersegmented neutrophils in the peripheral blood film is suggestive of megaloblastic changes in bone marrow.

The cytotoxic drug bleomycin can cause bleomycin-induced pneumonitis (BIP). It usually occurs during chemotherapy but can also occur up to six months post-therapy.

The patient is displaying signs and symptoms of hyperviscosity syndrome, secondary to the Waldenström’s macroglobulinemia. Treatment of choice is plasmapheresis.

Waldenström’s macroglobulinemia (also called lymphoplasmacytic lymphoma) is an uncommon type of non-Hodgkin lymphoma seen in older people. It is a lymphoplasmacytoid malignancy characterised by the secretion of a monoclonal IgM paraprotein. Its features include monoclonal IgM paraproteinemia; hyperviscosity syndrome leading to bilateral central retinal vein occlusion (CRVO) and hence, visual disturbances; weight loss and lethargy; hepatosplenomegaly and lymphadenopathy; and cryoglobulinemia. It is not, however, associated with bone pain.

Mycoplasma infection causes cold autoimmune haemolytic anaemia (AIHA). The rest of the aforementioned options cause warm AIHA.

AIHA may be divided into ‘warm’ and ‘cold’ types, according to the temperature at which the antibodies best cause haemolysis. It is most commonly idiopathic but may be secondary to a lymphoproliferative disorder, infection, or drugs.

1. Warm AIHA:
In warm AIHA, the antibody (usually IgG) causes haemolysis best at body temperature and tends to occur in extravascular sites, for example, spleen. Management options include steroids, immunosuppression, and splenectomy. It is caused by autoimmune diseases such as SLE (rarely causes mixed-type AIHA), cancers such as lymphomas and CLL, and drugs such as methyldopa.

2. Cold AIHA:
The antibody in cold AIHA is usually IgM and causes haemolysis best at 4°C and occurs more commonly intravascularly. Features may include symptoms of Raynaud’s disease and acrocyanosis. Patients do not respond well to steroids. Cold AIHA is caused by cancers such as lymphomas, and infections such as mycoplasma and EBV.

The direct Coombs test will specifically confirm immune-mediated haemolysis occurring post-transfusion in the aforementioned case.

There are two types of Coombs test used in immunohematology and immunology:

1. Direct Coombs test – It confirms autoimmune haemolytic anaemia by detecting antibodies or complement proteins attached to the surface of red blood cells.

2. Indirect Coombs test – It is used in prenatal testing of pregnant women and in testing prior to a blood transfusion. It detects antibodies floating freely in the blood, against foreign red blood cells.

Rasburicase should be given prior to chemotherapy in order to reduce the risk of tumour lysis syndrome (TLS). Rasburicase is a recombinant version of urate oxidase which is an enzyme that metabolizes uric acid to allantoin. Allantoin is 5-10 times more soluble than uric acid, hence, renal excretion is more effective.

TLS is a potentially fatal condition occurring as a complication during the treatment of high-grade lymphomas and leukaemias. It occurs from the simultaneous breakdown (lysis) of the tumour cells and subsequent release of chemicals into the bloodstream. This leads to hyperkalaemia and hyperphosphatemia in the presence of hyponatraemia. TLS can occur in the absence of chemotherapy, but it is usually triggered by the introduction of combination chemotherapy. Awareness of the condition is critical for its prophylactic management.

Burkitt lymphoma is a high-grade B-cell neoplasm. There are two major forms:
1. Endemic (African) form: typically involves maxilla or mandible.
2. Sporadic form: abdominal (e.g. ileocaecal) tumours are the most common form. More common in patients with HIV.

Burkitt lymphoma is associated with the c-myc gene translocation, usually t(8;14). The Epstein-Barr virus (EBV) is strongly implicated in development of the African form of Burkitt lymphoma and to a lesser extent, the sporadic form.

Management of the lymphoma is with chemotherapy. This tends to produce a rapid response which may cause TLS.

Warfarin inhibits the vitamin K-dependent procoagulants II, VII, IX, and X as well as anticoagulant protein C and S. It is highly protein-bound and can be displaced by a wide variety of drugs. It has a half-life of 36-48 hours.

Bleeding is the major side effect. Easy bruising, as seen in this case, is commonly seen in patients of warfarin overdose. Grossly prolonged PT and lesser increase in APTT may be seen in such cases.

Leukemoid reaction has a high LAP score.

Leukemoid reaction refers to leucocytosis occurring as a physiological response to stress or infection which may be mistaken for leukaemia, especially chronic myeloid leukaemia (CML). Leucocytosis occurs, initially, because of accelerated release of cells from the bone marrow and is associated with increased count of more immature neutrophils in the blood (left-shift). In order to differentiate, LAP score is used. Leukocytic alkaline phosphatase (ALP) activity is high in a leukemoid reaction but low in CML.

LAP score is high in:
1. Leukemoid reaction
2. Infections
3. Myelofibrosis
4. Polycythaemia rubra vera
5. Steroids, Cushing’s syndrome
6. Pregnancy, oral contraceptive pill

LAP score is low in:
1. CML
2. Pernicious anaemia
3. Paroxysmal nocturnal haemoglobinuria (PNH)
4. Infectious mononucleosis

Neutrophilia is also commonly associated with polycythaemia vera.

Polycythaemia vera (PV), also known as polycythaemia rubra vera, is a myeloproliferative disorder caused by clonal proliferation of marrow stem cells leading to an increase in red cell volume, often accompanied by overproduction of neutrophils and platelets. It has peak incidence in the sixth decade of life, with typical features including hyperviscosity, pruritus, splenomegaly, haemorrhage (secondary to abnormal platelet function), and plethoric appearance.

Some management options of PV include lose-dose aspirin, venesection (first-line treatment), hydroxyurea (slightly increased risk of secondary leukaemia), and radioactive phosphorus (P-32) therapy.

In PV, thrombotic events are a significant cause of morbidity and mortality. 5-15% of the cases progress to myelofibrosis or AML. The risk of having AML is increased with chemotherapy treatment.

B2-microglobulin is a useful marker of prognosis in multiple myeloma (MM). Raised levels imply a poorer prognosis. Low levels of albumin are also associated with a poor prognosis.

Methemoglobinemia is a rare condition in which the haemoglobin iron is in oxidized or ferric state (Fe3+) and cannot reversibly bind oxygen. Normally, the conversion of ferrous form of iron (Fe2+) to its ferric form (Fe3+) is regulated by NADH methaemoglobin reductase, which results in the reduction of methaemoglobin to haemoglobin. Disruption in the enzyme leads to increased methaemoglobin in the blood. There is tissue hypoxia as Fe3+ cannot bind oxygen, and hence the oxygen-haemoglobin dissociation curve is shifted to the left.

Methemoglobinemia can occur due to congenital or acquired causes. Congenital causes include haemoglobin variants such as HbM and HbH, and deficiency of NADH methaemoglobin reductase. Acquired causes are drugs (e.g. sulphonamides, nitrates, dapsone, sodium nitroprusside, and primaquine) and chemicals (such as aniline dyes).

The features of methemoglobinemia are cyanosis, dyspnoea, anxiety, headache, severe acidosis, arrhythmias, seizures, and loss of consciousness. Patients have normal pO2 but oxygen saturation is decreased. Moreover, presence of chocolate-brown coloured arterial blood (colour does not change with addition of O2) and brown urine also point towards the diagnosis of methemoglobinemia.

Burkitt lymphoma is a germinal centre B-cell-derived cancer that was instrumental in the identification of MYC as an important human oncogene more than three decades ago. Recently, new genomics technologies have uncovered several additional oncogenic mechanisms that cooperate with MYC to create this highly aggressive cancer.

Progressive hoarseness of the voice is a very typical and early finding in people suspected to have squamous cell laryngeal cancer. Due to mechanical compression, patients might experience dysphagia as well as pain. The ‘lump in the throat sensation is not uncommon too. Haemoptysis might be present, together with respiratory symptoms such as dyspnoea. Other symptoms consist of constitutional complaints, such as weight loss or fatigue.

This patient is a case of chronic myeloid leukaemia (CML) and should be started on imatinib as the first-line drug of choice.

Acute lymphoblastic leukaemia (ALL) is an aggressive type of blood and bone marrow cancer which can appear in childhood. Signs of childhood ALL include: Fever, Easy bruising, Petechiae, Bone or joint pain, Painless lumps in multiple areas of the body, Weakness, fatigue or paleness, and Loss of appetite. Blood tests may show elevated white blood cells, decreased values of red blood cells and low platelet count.

Prostate cancer is the most common primary tumour that metastasises to the bone.

Most common tumours causing bone metastasis (in descending order):
1. Prostate (32%)
2. Breast (22%)
3. Kidneys (16%)
4. Lungs
5. Thyroid

Most common sites of bone metastasis (in descending order):
1. Spine
2. Pelvis
3. Ribs
4. Skull
5. Long bones

A grossly elevated APTT may be caused by heparin therapy, haemophilia, or antiphospholipid syndrome. A normal factor VIIIc activity, however, points towards the diagnosis of haemophilia B, which is the deficiency of factor IX in the blood.

Haemophilia is an X-linked recessive disorder of coagulation. Up to 30% of patients have no family history of the condition. Haemophilia A is due to the deficiency of clotting factor VIII and is more common than haemophilia B, accounting for 90% of the cases. In haemophilia B (Christmas disease), there is a deficiency of clotting factor IX.

Characteristic features of haemophilia include hemarthrosis, haematomas, and prolonged bleeding following trauma or surgery. Coagulation profile of a haemophiliac person shows prolonged bleeding time, activated partial thromboplastin time (APTT), thrombin time (TT), but a normal prothrombin time (PT).

Lead poisoning is characterised by abdominal pain, fatigue, constipation, peripheral neuropathy (mainly motor), and blue lines on gum margin in 20% of the adult patients (very rare in children).

For diagnosis, the level of lead in blood is usually considered with levels greater than 10 mcg/dL being significant. Furthermore, the blood film shows microcytic anaemia and basophilic stippling of red blood cells. Urinary coproporphyrin is increased (urinary porphobilinogen and uroporphyrin levels are normal to slightly increased). Raised serum and urine levels of delta-aminolaevulinic acid may also be seen, making it sometimes difficult to differentiate from acute intermittent porphyria.

This is a typical picture of acute chest syndrome (ACS). According to the British Committee for Standards in Haematology (BCSH), ACS is defined as ‘an acute illness characterised by fever and/or respiratory symptoms, accompanied by a new pulmonary infiltrate on chest X-ray’. ACS occurs in sequestration crisis, which is one of the four main types of crises occurring in sickle cell disease.

The fundamentals of initial management are as follows:
1. Oxygen therapy to maintain saturation >95%
2. Intravenous fluids to ensure euvolemia
3. Adequate pain relief
4. Incentive spirometry in all patients presenting with rib or chest pain
5. Antibiotics with cover for atypical organisms
6. Bronchodilators if asthma co-exists with acute chest syndrome, or if there is an evidence of acute bronchospasm on auscultation
7. Early consultation with the critical care team and haematology department

A senior haematologist then makes a decision as to whether a simple or exchange transfusion is necessary in order to achieve a target Hb of 10.0-11.0g/dL in either instance.

Sickle Cell Crises:
Sickle cell anaemia is characterised by periods of good health with intervening crises:
1. Sequestration crisis: acute chest syndrome (i.e. fever, dyspnoea, chest/rib pain, low pO2, and pulmonary infiltrates)

2. Thrombotic (painful or vaso-occlusive) crisis: precipitated by infection, dehydration, and deoxygenation

3. Aplastic crisis: sudden fall in haemoglobin without marked reticulocytosis, usually occurring secondary to parvovirus infection

4. Haemolytic crisis: fall in haemoglobin secondary to haemolysis, rare type of sickle cell crises

Individuals with thalassemia major usually develop symptoms within the first two years of life. These infants may fail to thrive and often have difficulty feeding, tire easily and suffer from severe anemia.

The infants may also suffer from diarrhea, irritability, recurrent episodes of fever, and other intestinal problems. These children have trouble gaining weight and growing at the rate expected for their age. Other complications include enlarged spleen, heart and liver and misshapen bones.

In many cases, the symptoms are severe enough to warrant regular blood transfusion to replenish the blood with healthy red blood cells. However, these regular transfusions can lead to a build up of iron in the blood that can damage the heart, liver and endocrine system and chelation therapy may be needed to remove this iron from the body.

Individuals with beta thalassemia trait usually have evidence of microcytosis and increased levels of hemoglobin A2. Hemoglobin F is sometimes elevated as well. Individuals with alpha thalassemia trait usually have evidence of microcytosis and normal levels of hemoglobin A2 and F.

In thalassemia major, the hemoglobin (Hb) level is usually less than 7 g/dl; the mean corpuscolar volume (MCV) less than 70 fl and the mean corpuscolar Hb (MCH) is over 20 pg.

In thalassemia intermedia, the hemoglobin level is between 7 and 10 g/dl; the MCV between 50 and 80 fl and MCH between 16 and 24 pg.

Thalassemia minor is characterized by a reduced MCV and MCH and an increased haemoglobin A2 level.

The risk factors for bladder cancer are:

1. Smoking
2. Exposure to aniline dyes in the printing and textile industry
3. Exposure to rubber manufacturing
4. Cyclophosphamides
5. Schistosomiasis.

NICE guidelines on hypercalcemia recommend that maintaining good hydration equals drinking 3-4 L of fluid/day, provided there are no contraindications. A low calcium diet is not necessary because intestinal absorption of calcium is reduced. The patient should avoid any other drugs or vitamins that could worsen the hypercalcemia. Mobilization is encouraged and any symptoms of hypercalcemia should be reported.

Transfusion-related acute lung injury (TRALI) is a serious complication of blood transfusion characterised by the acute onset of non-cardiogenic pulmonary oedema following transfusion of blood products.

TRALI is a more severe manifestation of the febrile non-haemolytic group of transfusion reactions and usually occur in patients who have had multiple previous transfusions. TRALI is related to leucocyte antibodies which are present in the plasma of the blood donor. Multiparous women are the highest-risk donors for TRALI.

For management, leucocyte-depleted blood is now used for transfusion and this is associated with a reduced risk of this type of transfusion reaction.

The patient is most likely suffering from Waldenström’s macroglobulinemia in which IgM paraproteinemia is found. Hyperviscosity syndrome can occur in the patients accounting for 10-15% of the cases.

Waldenström’s macroglobulinemia (also called lymphoplasmacytic lymphoma) is an uncommon type of non-Hodgkin lymphoma seen in older people. It is a lymphoplasmacytoid malignancy characterised by the secretion of a monoclonal IgM paraprotein. Its features include monoclonal IgM paraproteinemia; hyperviscosity syndrome leading to bilateral central retinal vein occlusion (CRVO) and hence, visual disturbances; weight loss and lethargy; hepatosplenomegaly and lymphadenopathy; and cryoglobulinemia. It is not, however, associated with bone pain.

This is a classical picture of graft versus host disease (GVHD) following bone marrow transplant. Acute GVHD occurs in the first 100 days post transplant with chronic GVHD occurring 100-300 days after transplant. GVHD is graded according to the Seattle system, and each organ involved is scored (skin, liver, and gut).

The standard initial treatment in the acute setting is high-dose methylprednisolone started immediately. If there is no response, a more intensive immunosuppressive agent such as alemtuzumab or antilymphocyte globulin is needed.