PE26.1-17 | Hemato-Oncology — Glossary

The standard first-line chemotherapy regimen for Hodgkin lymphoma: Adriamycin (doxorubicin), Bleomycin, Vinblastine, Dacarbazine; administered in 28-day cycles; one of the most successful cancer regimens with long-term cure in the majority of patients.

A coagulation test that measures the time for plasma to clot in the presence of phospholipid and an activator (ellagic acid/kaolin), testing the intrinsic and common pathways; normal approximately 25–35 seconds; prolonged in hemophilia A and B.

A malignant clonal disorder of lymphoid progenitor cells characterised by the arrest and uncontrolled proliferation of immature lymphoblasts, leading to bone marrow failure and extramedullary infiltration; the most common childhood malignancy.

Acquired haemolytic anaemia caused by autoantibodies directed against RBC surface antigens; warm type (IgG, most common in children) causes extravascular haemolysis; diagnosed by a positive direct Coombs test; treated with prednisolone 1–2 mg/kg/day.

A CD30-positive T-cell NHL; in children usually ALK-positive (from NPM-ALK fusion via t(2;5)); ALK positivity confers a better prognosis; treated with CHOP-based chemotherapy.

A xanthine oxidase inhibitor that blocks the conversion of hypoxanthine and xanthine to uric acid; used prophylactically before chemotherapy in ALL to prevent hyperuricaemia and urate nephropathy from tumour lysis.

Reduction in haemoglobin concentration below the age-specific normal reference range, leading to reduced oxygen-carrying capacity; defined by WHO/IAP cut-offs varying from <11 g/dL (under 5 years) to <13 g/dL (adult males).

The Government of India's National Anaemia Control Programme strategy (launched 2018) targeting six beneficiary groups (under-5 children, school children, adolescents, pregnant women, lactating mothers, reproductive-age women) with IFA supplementation, deworming, and dietary counselling.

Anaemia occurring in the setting of prolonged inflammatory, infectious, or neoplastic conditions; mediated by hepcidin-induced iron sequestration and reduced EPO responsiveness; typically normocytic but may be mildly microcytic.

The staging system for Hodgkin lymphoma (and some NHL): Stage I (single nodal region), II (≥2 regions, same side of diaphragm), III (both sides), IV (extranodal: bone marrow, liver, lung); suffix A = no B symptoms, B = B symptoms present.

Rh-specific IgG that coats Rh-positive red blood cells, creating a competing substrate for splenic macrophage Fc receptors and thereby sparing antibody-coated platelets from destruction; effective only in Rh-positive, non-splenectomised patients.

A transient cessation of erythropoiesis caused by parvovirus B19 infection of erythroid progenitor cells; causes a sudden dramatic fall in haemoglobin with absent reticulocytes in patients with chronic haemolytic anaemia (HS, SCD, thalassaemia); a paediatric haematological emergency requiring transfusion.

A pink, needle-like intracytoplasmic inclusion in myeloblasts, formed from fused lysosomes; pathognomonic of acute myeloid leukaemia (AML); never seen in ALL or normal cells.

A prognostically significant triad in lymphoma staging: unexplained fever >38°C, drenching night sweats, and unexplained weight loss >10% body weight over 6 months; designated by the suffix 'B' in Ann Arbor staging; their presence indicates more advanced or aggressive disease.

ALL arising from transformation of a B-lymphoid progenitor arrested at the pre-B or early pre-B stage; ~85% of childhood ALL; immunophenotype CD19+, CD10+, TdT+; generally better prognosis than T-ALL.

The clinical principle that B12 deficiency must be excluded or treated before or concurrently with folate supplementation; administering folate alone to a B12-deficient patient corrects the haematological picture but allows neurological damage (subacute combined degeneration) to progress undetected.

A chimeric oncogene arising from the t(9;22)(q34;q11) translocation, present in ~3–5% of childhood ALL and 25–30% of adult ALL; encodes a constitutively active tyrosine kinase; now treated with tyrosine kinase inhibitors (TKIs) such as imatinib or dasatinib added to chemotherapy.

A heterozygous carrier state for a beta-globin mutation, characterised by mild microcytic anaemia, elevated HbA2 (>3.5%), and no transfusion dependence; important to identify for genetic counselling.

A laboratory test measuring factor inhibitor titre; one Bethesda unit (BU) is the amount of inhibitor that neutralises 50% of factor VIII (or IX) in 1 mL of normal plasma; high-responders have >5 BU and require bypassing agents.

Red blood cells with a semicircular bite out of the edge, produced when splenic macrophages remove Heinz body inclusions from G6PD-deficient RBCs; highly specific for oxidant haemolysis (G6PD deficiency).

An immature haematopoietic precursor cell with a high nuclear-to-cytoplasmic ratio, fine chromatin, and prominent nucleoli; presence on peripheral smear is always abnormal and raises urgent suspicion for acute leukaemia.

A procedure to obtain a sample of bone marrow from the posterior superior iliac spine (children >18 months) or anterior tibia (infants), used to diagnose haematological malignancies, aplastic anaemia, and storage disorders.

A highly aggressive mature B-cell NHL characterised by MYC translocation (t(8;14) in ~80%), 'starry-sky' histology, and the fastest doubling time of any human tumour; endemic form (jaw/orbital, EBV ~100%) and sporadic form (abdominal, EBV ~20–30%); exquisitely chemosensitive.

A heterozygous female with one normal and one mutant X chromosome for a haemophilia gene; typically asymptomatic due to adequate factor from the normal allele, but transmits the defective allele to 50% of sons (affected) and 50% of daughters (carriers).

ITP lasting >12 months; more common in adults than children; most childhood ITP does not become chronic.

Leukaemic CNS involvement defined as ≥5 WBCs/µL in the CSF with blasts identified on cytospin; requires intensification of CNS-directed therapy including additional intrathecal chemotherapy.

An intensive alternating short-course chemotherapy regimen for Burkitt lymphoma (cyclophosphamide, vincristine, doxorubicin, high-dose methotrexate alternating with ifosfamide, etoposide, high-dose cytarabine); includes intrathecal CNS prophylaxis; achieves cure in the majority of patients.

A condition in toddlers consuming large volumes of cow's milk (>500 mL/day) in which cow's milk proteins cause low-grade intestinal inflammation with occult rectal bleeding, contributing to IDA through chronic iron loss; cow's milk also inhibits iron absorption simultaneously.

A blood product prepared by slow thawing of fresh frozen plasma; rich in factor VIII, von Willebrand factor, fibrinogen, and factor XIII; used as an alternative to factor concentrate when concentrates are unavailable.

A synthetic analogue of vasopressin that stimulates endothelial release of stored von Willebrand factor (vWF) and factor VIII, raising FVIII levels 3–6-fold; effective only in mild hemophilia A (baseline FVIII 5–40%) and not in hemophilia B.

A diagnosis made by systematically ruling out all other identifiable causes; ITP is classified this way because no specific confirmatory test exists — the diagnosis depends on finding isolated thrombocytopenia without evidence of another aetiology.

A laboratory test that detects IgG antibodies or complement (C3d) bound to the surface of red blood cells; positive in AIHA and haemolytic disease of the newborn; negative in all congenital haemolytic conditions (G6PD, HS, thalassaemia, SCD); the key test distinguishing immune from non-immune haemolysis.

A bruise > 1 cm; may occur in both platelet-type and coagulation-type bleeding disorders, but platelet ecchymoses are typically superficial and follow minor trauma.

The active iron content in an iron supplement formulation; the dose of iron therapy is expressed as elemental iron (3–6 mg/kg/day), not as the weight of the salt; ferrous sulphate 200 mg tablet contains 65 mg elemental iron.

Surgical removal of an entire lymph node for histopathological examination; the gold standard for lymphoma diagnosis as it preserves nodal architecture, which is essential for subtype classification; FNAC alone is inadequate for lymphoma diagnosis.

An alloantibody (usually IgG) that neutralises infused factor VIII or IX; develops in ~25–30% of patients with severe hemophilia A after repeated replacement therapy; detected by the Bethesda assay.

A vitamin K-dependent serine protease of the intrinsic pathway; with factor VIIIa as cofactor it forms the intrinsic tenase complex activating factor X; deficient in hemophilia B.

A plasma coagulation protein that acts as a cofactor to factor IXa in the intrinsic tenase complex, enabling rapid activation of factor X; its gene is located at Xq28 and is deficient in hemophilia A.

A surface receptor on macrophages and other immune cells that binds the Fc region of IgG antibodies; in ITP, Fc-receptor-bearing splenic macrophages engulf platelets opsonised with anti-platelet IgG.

The intracellular iron-storage protein; serum ferritin is the most sensitive and specific marker of iron stores — reduced (<12 µg/L) in iron deficiency, elevated in infection/inflammation (acute-phase reactant).

Protoporphyrin that accumulates in Stage 2 iron deficiency when haem synthesis is blocked (no iron to incorporate); elevated FEP is an early marker of iron-deficient erythropoiesis, preceding the fall in haemoglobin.

The most common enzyme deficiency worldwide; X-linked recessive; glucose-6-phosphate dehydrogenase is required to generate NADPH for antioxidant defence in RBCs; deficiency causes episodic haemolysis triggered by oxidant stress (drugs, fava beans, infections).

A platelet surface integrin (αIIbβ3) that normally mediates platelet aggregation by binding fibrinogen; the primary autoantigen in ITP, targeted by pathogenic IgG autoantibodies.

Megaloblastic anaemia (folate-deficient type) occurring in infants fed exclusively on goat's milk, which is markedly deficient in folate (approximately 6 µg/L vs 50 µg/L in human breast milk); infants develop macrocytic anaemia, failure to thrive, and anorexia, often around 4–6 months of age.

A clinical grading scale for splenomegaly from Grade 0 (not palpable) to Grade V (crosses the midline), widely used in tropical and paediatric medicine to standardise spleen size documentation.

Iron bound within the haem ring of myoglobin and haemoglobin in animal flesh; bioavailability ~25%, not affected by dietary inhibitors; found in meat, poultry, and fish; contrasted with non-haem iron from plant sources (~5–10% bioavailability).

Bleeding into a joint cavity, the hallmark of severe hemophilia; characterised by warmth, swelling, pain, and limited movement; repeated bleeds cause haemophilic arthropathy.

Transplantation of donor (allogeneic) haematopoietic stem cells after myeloablative conditioning; reserved in ALL for high-risk relapsed or refractory disease, or primary high-risk cases with inadequate MRD response.

A laboratory technique that separates haemoglobin variants by their electrical charge at defined pH; used to diagnose haemoglobinopathies by quantifying HbA, HbA2, HbF, HbS, and other variants.

The presence of free haemoglobin in the urine, giving it a dark brown or red-black ('cola' or 'Coca-Cola') colour; indicates intravascular haemolysis (complement-mediated or mechanical) where plasma haemoglobin exceeds haptoglobin binding capacity and is filtered by the glomerulus.

Anaemia resulting from premature destruction of red blood cells (shortened RBC lifespan <120 days), presenting with the triad of anaemia, unconjugated jaundice, and splenomegaly, with elevated reticulocytes, elevated LDH, and reduced haptoglobin.

A minor adult haemoglobin fraction (α₂δ₂), normally 2–3.5% of total haemoglobin; elevation above 3.5% is the hallmark of beta-thalassaemia trait (carrier state).

Haemoglobin with alpha and gamma chains (α₂γ₂), predominant before 6 months of age; persistence beyond 6 months in large quantities indicates beta-thalassaemia major, HPFH, or sickle-related conditions.

Precipitates of denatured, oxidised haemoglobin that attach to the inner RBC membrane in G6PD deficiency; visible only on supravital stain (crystal violet or brilliant cresyl blue), not on standard Leishman stain; their removal by the spleen produces bite cells.

A hereditary coagulation disorder caused by deficiency of factor VIII (FVIII), inherited in an X-linked recessive pattern; the most common hereditary coagulopathy, affecting ~1 in 5,000 male births.

A hereditary coagulation disorder caused by deficiency of factor IX (FIX), X-linked recessive, affecting ~1 in 30,000 males; clinically indistinguishable from hemophilia A but requires FIX replacement.

A liver-produced peptide hormone that is the master regulator of iron homeostasis; it reduces intestinal iron absorption and traps iron in macrophages, elevated in inflammation causing anaemia of chronic disease.

The most common hereditary haemolytic anaemia in Northern European populations; autosomal dominant (75%); mutations in RBC membrane proteins (spectrin, ankyrin) cause membrane vesiculation and spherocyte formation; splenectomy after age 5–6 is curative.

Heart failure characterised by an elevated cardiac output, occurring in severe anaemia (Hb <5 g/dL) as the heart attempts to maintain oxygen delivery by increasing flow; features include tachycardia, flow murmur, cardiomegaly, and hepatomegaly.

A malignant lymphoid neoplasm characterised by the presence of Reed-Sternberg cells in a reactive inflammatory infiltrate; arises from germinal centre B cells; spreads contiguously along lymphatic chains; bimodal age distribution with adolescent peak; excellent prognosis with modern chemotherapy.

An intermediate in methionine metabolism; elevated in both B12 and folate deficiency (both vitamins are required for homocysteine remethylation to methionine); not specific for either deficiency, but its elevation confirms megaloblastic biochemistry when combined with other findings.

A form of vitamin B12 used for intramuscular injection in B12 deficiency; preferred over cyanocobalamin for IM use because it is retained in tissues longer and is more suitable for patients with cyanide exposure risk; standard dose for neurological B12 deficiency in children: 1000 µg IM.

An oral cytoreductive agent that increases fetal haemoglobin (HbF) production in sickle cell disease; HbF inhibits HbS polymerisation, reducing crisis frequency by ~50%; dose 15–20 mg/kg/day; monitor FBC for myelosuppression.

A cytogenetic abnormality in which leukaemic blasts contain more than 50 chromosomes; associated with the best prognosis in childhood B-ALL (~90% EFS); blasts are exquisitely sensitive to antimetabolites.

A neutrophil with five or more nuclear lobes, or any neutrophil with six or more lobes; the earliest peripheral blood sign of megaloblastic change, appearing 2–4 weeks before MCV rises above 100 fL; even one 6-lobed neutrophil is diagnostic.

A condition where an enlarged spleen excessively sequesters and destroys blood cells, leading to cytopenias (anaemia, leukopenia, thrombocytopenia) despite an active bone marrow; an indication for splenectomy when severe.

A red blood cell with a pale centre occupying more than one-third of the cell diameter, reflecting reduced haemoglobin content per cell; characteristic of iron deficiency anaemia.

An acquired immune-mediated disorder characterised by isolated thrombocytopenia (platelet count <150,000/µL) caused by autoantibody-mediated platelet destruction and impaired production, in the absence of other identifiable causes.

The first treatment phase (~4 weeks) of ALL aimed at achieving complete remission (marrow blasts <5%); standard drugs include vincristine, prednisolone/dexamethasone, and L-asparaginase; an anthracycline is added for high-risk disease.

A process in which the bone marrow is hyperactive (producing many megaloblastic precursors) but the output of mature red cells into the circulation is low, because the abnormal precursors are destroyed within the marrow (intramedullary haemolysis); explains the paradox of a low reticulocyte count despite severe megaloblastic anaemia.

Bleeding within the cranial vault; the most feared complication of severe ITP (platelet <10,000/µL); occurs in <0.5% of ITP cases but carries high morbidity and mortality.

Methotrexate injected directly into the subarachnoid space via lumbar puncture; used as CNS prophylaxis and treatment in ALL; has replaced prophylactic cranial irradiation, which causes neurocognitive sequelae.

A pooled preparation of human IgG used to saturate Fc receptors on splenic macrophages, thereby reducing their phagocytosis of antibody-coated platelets; produces a rapid rise in platelet count within 24–48 hours.

The coagulation sequence initiated by contact of blood with subendothelial collagen: factor XII activates XI → IX; IX + VIII activate X; defects here prolong the aPTT.

A glycoprotein secreted by gastric parietal cells; binds vitamin B12 in the stomach and escorts the complex to the terminal ileum where B12 is absorbed; absent in congenital intrinsic factor deficiency and autoimmune (juvenile pernicious) anaemia, necessitating parenteral B12 therapy.

Radiotherapy directed to the initially involved lymph node regions in Hodgkin lymphoma; combined with chemotherapy in advanced-stage or bulky disease; increasingly omitted in paediatric protocols for early-stage good responders to reduce late effects.

Treatment to remove excess iron accumulated from repeated blood transfusions in thalassaemia major; started when serum ferritin >1000 µg/L; agents include desferrioxamine (SC), deferasirox (oral, once daily), and deferiprone (oral, most effective for cardiac iron).

The most common nutritional anaemia, characterised by depletion of body iron stores leading to inadequate haem synthesis; produces a microcytic hypochromic anaemia with low ferritin, elevated TIBC, and low transferrin saturation.

A chromosomal rearrangement involving the KMT2A (Mixed Lineage Leukaemia) gene at 11q23; characteristic of infant ALL (<1 year); associated with very poor prognosis due to chemotherapy resistance.

Spoon-shaped nails with upward curvature and thinning, caused by defective keratin production in iron deficiency; a specific but late sign of severe iron depletion.

An enzyme derived from E. coli or Erwinia that depletes serum asparagine; ALL blasts lack asparagine synthetase and depend on exogenous asparagine, making them selectively susceptible to asparaginase-mediated starvation.

An immature lymphoid precursor cell; in ALL, morphologically characterised by a high nuclear-to-cytoplasm ratio, fine chromatin, and inconspicuous nucleoli; ≥25% in the bone marrow defines ALL.

A large, oval-shaped red blood cell with no central pallor, specific to megaloblastic haematopoiesis; distinct from the round macrocytes of liver disease and hypothyroidism; produced when DNA synthesis is impaired but cytoplasmic growth continues.

Anaemia with MCV >100 fL; most commonly megaloblastic (B12 or folate deficiency) in children; non-megaloblastic causes include liver disease and hypothyroidism.

The average volume of a red blood cell in femtolitres; normal 80–100 fL; the primary index for classifying anaemia as microcytic, normocytic, or macrocytic.

The average volume of a single red blood cell, measured in femtolitres (fL); used to classify anaemia as microcytic (<72 fL in children), normocytic, or macrocytic (>100 fL).

An abnormally large erythroid precursor in the bone marrow produced when DNA synthesis is impaired; characterised by nuclear-cytoplasmic asynchrony — the nucleus remains immature while the cytoplasm matures; the precursor of macro-ovalocytes in the peripheral blood.

A macrocytic anaemia caused by impaired DNA synthesis (from B12 or folate deficiency), producing large erythroid and myeloid precursors (megaloblasts) with nuclear-cytoplasmic asynchrony; the hallmarks on peripheral smear are macro-ovalocytes and hypersegmented neutrophils.

An abnormally large platelet released from megakaryocytes under conditions of heightened thrombopoietic drive; their presence on peripheral smear in thrombocytopenia suggests increased platelet turnover, consistent with ITP.

MCV divided by RBC count; a value <13 suggests thalassaemia trait (high RBC count, small cells), while >13 suggests iron deficiency anaemia (low RBC count, small cells); a screening tool, not diagnostic.

The accumulation of folate as 5-methylTHF (its inactive stored form) when B12 is deficient; B12 is required to accept the methyl group from 5-methylTHF to regenerate active folate (5,10-methyleneTHF for DNA synthesis); hence B12 deficiency causes functional folate deficiency even when folate stores are adequate.

A metabolite that accumulates in B12 deficiency when the B12-dependent enzyme methylmalonyl-CoA mutase is impaired; elevated serum or urine MMA is the most specific biochemical marker of B12 deficiency, distinguishing it from folate deficiency.

Anaemia with MCV <80 fL, indicating small red blood cells; principal causes in children are iron deficiency anaemia and thalassaemia.

Anaemia characterised by small red cells (low MCV) with reduced haemoglobin content (low MCH and pale central zone); most commonly caused by iron deficiency or thalassaemia in children.

Submicroscopic residual leukaemic cells undetectable by morphology but detectable by flow cytometry (immunophenotype) or PCR (clone-specific markers); MRD response at specific time points during therapy is the strongest predictor of long-term outcome.

A proposed mechanism by which viral antigens share structural similarity with host molecules (e.g., platelet glycoproteins), triggering an immune response that cross-reacts with self-tissues.

The staging system for childhood Non-Hodgkin lymphoma: Stages I–IV reflecting extent of disease, with Stage IV defined by bone marrow (<25% blasts) or CNS involvement; designed to capture the non-contiguous and extranodal nature of childhood NHL.

In Burkitt lymphoma, a chromosomal rearrangement — most commonly t(8;14) — juxtaposing the MYC proto-oncogene to the immunoglobulin heavy chain (IgH) locus, causing constitutive MYC overexpression and uncontrolled B-cell proliferation.

ITP within the first 3 months of diagnosis; the term replaces older terminology such as 'acute ITP'.

Iron from plant sources (legumes, dark leafy vegetables, fortified cereals) and dairy; bioavailability ~5–10%; significantly reduced by phytates, polyphenols, and calcium, and enhanced by vitamin C (ascorbic acid).

A heterogeneous group of lymphoid malignancies that do not contain Reed-Sternberg cells; in children predominantly high-grade and aggressive (Burkitt, T-lymphoblastic, DLBCL, ALCL); spreads non-contiguously and frequently involves extranodal sites.

Anaemia with MCV 80–100 fL; includes haemolytic anaemias, aplastic anaemia, acute blood loss, and anaemia of chronic disease.

Abnormal enlargement of an organ; in haematology, refers most commonly to hepatomegaly (liver enlargement) or splenomegaly (spleen enlargement) as seen in haemolytic anaemias, infiltrative malignancy, and portal hypertension.

A diagnostic test for hereditary spherocytosis in which RBCs are exposed to progressively hypotonic NaCl solutions; spherocytes lyse at higher salt concentrations (e.g., 0.5% NaCl) than normal RBCs (0.45%), reflecting their reduced ability to swell before rupturing.

A life-threatening septicaemia, typically with encapsulated organisms (S. pneumoniae, H. influenzae, N. meningitidis), occurring after splenectomy; risk is highest in children under 5 years and can be fatal within 12–24 hours.

Transfusion of concentrated red blood cells (haematocrit ~70%) at 10–15 mL/kg over 3–4 hours, indicated in symptomatic anaemia with Hb <7 g/dL or haemodynamic compromise.

Reduction in all three peripheral blood cell lines — red blood cells (anaemia), white blood cells (leucopenia), and platelets (thrombocytopenia) — occurring in severe megaloblastic anaemia because the DNA synthesis block affects erythroid, myeloid, and megakaryocytic precursors in the bone marrow simultaneously.

Elongated, cigar-shaped erythrocytes (also called elliptocytes in the context of IDA); seen on peripheral blood smear in severe iron deficiency anaemia; highly specific for IDA when found alongside hypochromic microcytic cells.

Long-term oral phenoxymethylpenicillin (penicillin V) given after splenectomy to reduce OPSI risk; 125 mg twice daily for children <5 years, 250 mg twice daily for ≥5 years, continued for ≥2 years and until age 5 in all children.

A glass-slide preparation of blood stained with Leishman or Wright-Giemsa stain; allows morphological classification of RBCs (hypochromic, macrocytic, spherocytes, sickle cells) and detection of Heinz bodies, hypersegmented neutrophils, and parasites.

ITP lasting 3–12 months from diagnosis; includes patients who did not achieve spontaneous remission and those who lost treatment response.

A functional-anatomical imaging modality using FDG (fluorodeoxyglucose) to detect metabolically active tumour tissue; the gold standard for staging and response assessment in Hodgkin lymphoma; used to guide adaptive therapy (whether to add or omit radiotherapy based on interim response).

Pinpoint (< 3 mm), non-blanching haemorrhagic spots in the skin or mucous membranes resulting from platelet-type bleeding; they do not fade on pressure and do not represent capillary dilatation.

A persistent craving to ingest non-nutritive, non-food substances (soil, clay, ice, paper); associated with iron deficiency anaemia and may represent an attempt to obtain missing minerals.

Overwhelming post-splenectomy infection — a rare but potentially fatal sepsis from encapsulated organisms (Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae) in asplenic patients; risk is highest in children <5 years and within 2 years of splenectomy; prevented by pre-operative vaccines and penicillin prophylaxis.

The bony prominence at the posterolateral iliac bone, the preferred BMA site in children over 18 months; superficial, flat, and away from vital structures.

Regular infusion of factor concentrate (typically 2–3 times per week or every other day) in severe hemophilia to maintain minimum factor levels >1% and prevent spontaneous bleeds, especially haemarthrosis; now the standard of care for severe hemophilia.

A coagulation test measuring clot formation after addition of tissue factor (thromboplastin), testing the extrinsic and common pathways; normal in hemophilia A and B because factor VII (extrinsic) is intact.

Non-blanching haemorrhagic lesions in the skin, 3–10 mm in diameter, caused by red cell extravasation; characteristic of thrombocytopenia and vasculitis.

A recombinant urate oxidase that degrades existing uric acid to allantoin (more soluble); used for rapid treatment of established hyperuricaemia in TLS or as prophylaxis in high-risk cases; contraindicated in G6PD deficiency.

A measure of the variability in red blood cell size (anisocytosis); normally 11.5–14.5%; markedly elevated in iron deficiency anaemia, reflecting the production of increasingly smaller cells as iron depletes.

Elevated platelet count (thrombocytosis) occurring as a secondary response to iron deficiency anaemia; useful corroborating finding on CBC; resolves with iron treatment.

A measure of the degree of variation in red cell size (anisocytosis); elevated RDW indicates iron deficiency anaemia (heterogeneous population), while a normal RDW with microcytosis suggests thalassaemia trait (uniformly small cells).

The folate content of red blood cells, reflecting long-term (2–3 month) body folate stores; more reliable than serum folate (which reflects recent dietary intake) for diagnosing folate deficiency; normal >150 ng/mL; may be falsely low in B12 deficiency (methylfolate trap).

The pathognomonic cell of Hodgkin lymphoma — a large binucleate or multinucleate cell with prominent eosinophilic 'owl-eye' nucleoli; derived from a germinal centre B cell that has escaped apoptosis; immunophenotype CD15+, CD30+, CD45−.

The percentage of immature (RNA-containing) red blood cells in peripheral blood; elevated (>2%) in haemolytic anaemia or blood loss indicating active erythropoietic response; reduced in hypoproliferative anaemias.

An early rise in immature red blood cells (reticulocytes) in the peripheral blood following initiation of effective iron therapy; typically detectable by day 7–10 and represents the bone marrow's response to replenished substrate.

Classification of ALL into standard-risk and high-risk groups based on age, initial WBC count, immunophenotype, cytogenetics, and early MRD response; determines the intensity of chemotherapy and eligibility for stem cell transplantation.

An elongated, crescent-shaped red blood cell with pointed ends, formed when deoxygenated HbS polymerises; pathognomonic of sickle cell disease (HbSS) on peripheral smear.

Autosomal recessive haemoglobin disorder (HbSS) caused by a valine-for-glutamic-acid substitution at position 6 of the beta-globin chain; deoxygenated HbS polymerises, causing RBC sickling, vasoocclusion (pain crises), haemolysis, and progressive organ damage; HbF is protective.

A small, round, densely haemoglobinised red cell lacking central pallor; seen in hereditary spherocytosis (osmotic fragility test positive) and autoimmune haemolytic anaemia (direct antiglobulin test positive).

Surgical removal of the spleen; considered in refractory chronic ITP as it removes the major site of platelet destruction and autoantibody production; deferred in children due to the risk of post-splenectomy sepsis.

An acute emergency in sickle cell disease where blood becomes rapidly trapped in the spleen, causing sudden massive splenomegaly and a drop in haemoglobin of ≥2 g/dL from baseline; requires immediate transfusion and transfer.

Three sequential stages: Stage 1 (storage depletion — low ferritin, normal Hb/MCV), Stage 2 (iron-deficient erythropoiesis — low ferritin + low transferrin saturation, Hb near-normal), Stage 3 (frank IDA — low Hb, microcytic hypochromic RBCs); Stage 1 and 2 are subclinical.

A histological appearance in Burkitt lymphoma: a uniform background of high-mitotic blasts punctuated by scattered pale macrophages that have ingested apoptotic tumour cells; resembles stars in a night sky; reflects the extremely high proliferation and apoptosis rate.

A neurological complication unique to B12 deficiency, characterised by demyelination of both the dorsal columns (posterior column signs: loss of vibration sense and proprioception) and the corticospinal tracts (upper motor neurone signs); caused by toxic accumulation of methylmalonyl-CoA disrupting myelin synthesis.

A clinical syndrome caused by compression or obstruction of the superior vena cava, usually by a mediastinal mass; presents with facial oedema, arm oedema, distended neck veins, headache, and dyspnoea; a medical emergency in the context of mediastinal lymphoma.

ALL arising from transformation of a T-lymphoid progenitor in the thymus; ~15% of childhood ALL; presents with mediastinal mass, high WBC, and CNS involvement; immunophenotype CD3+, CD7+, TdT+; generally high-risk.

A T-cell neoplasm of lymphoid origin closely related to T-ALL; presents with mediastinal mass (thymic origin), SVC syndrome, and CNS tropism; classified as lymphoma when bone marrow blasts are <25%; classified as T-ALL when ≥25%.

A red cell with a bull's-eye appearance (central density, pale ring, dense periphery) due to increased surface-to-volume ratio; seen in thalassaemia, liver disease, HbC disease, and post-splenectomy states.

A joint that has sustained ≥3 clinically apparent bleeds within a 6-month period; target joints in hemophilia develop progressive synovitis, cartilage destruction, and eventual haemophilic arthropathy.

The enzymatic complex on activated platelet phospholipid membranes comprising activated factor IXa and its cofactor factor VIIIa; converts factor X to Xa; the non-functional site of defect in both hemophilia A and B.

Homozygous beta-thalassaemia; absent or severely reduced beta-globin chain synthesis causes profound haemolytic anaemia presenting after 6 months of age when HbF declines; requires lifelong regular transfusions and iron chelation; only curative treatment is bone marrow transplantation.

The characteristic facial appearance of untransfused or under-transfused thalassaemia major patients: frontal bossing, prominent malar eminences, protrusion of upper teeth, and saddle-nose deformity, caused by expansion of the erythroid marrow into the facial bones in response to chronic anaemia.

A platelet count below 150,000/µL; classified as mild (100,000–150,000), moderate (50,000–100,000), or severe (<50,000); below 20,000/µL there is significant risk of spontaneous bleeding.

A thrombotic microangiopathy (TMA) characterised by the pentad of thrombocytopenia, microangiopathic haemolytic anaemia (schistocytes on smear), fever, renal failure, and neurological abnormalities; distinguished from ITP by the presence of schistocytes and multi-system involvement.

The maximum amount of iron that transferrin in the blood can bind; elevated in iron deficiency as more transferrin is synthesised to capture scarce iron, reduced in anaemia of chronic disease.

An antifibrinolytic agent that inhibits plasminogen activators, preventing fibrin clot dissolution; used as an adjunct in hemophilia for mucosal bleeds (oral, nasal) and dental procedures.

Serum iron ÷ TIBC × 100%; indicates the proportion of iron-binding sites on transferrin that are occupied; reduced in IDA (<15%), elevated in iron overload.

The semi-lunar area in the left lower chest bounded by the left costal margin, the anterior axillary line, and the 6th rib; normally tympanitic on percussion; obliteration (dullness) indicates splenomegaly.

A metabolic emergency caused by rapid destruction of malignant cells releasing intracellular contents: hyperkalaemia, hyperphosphataemia, hyperuricaemia, and secondary hypocalcaemia; can precipitate acute kidney injury, cardiac arrhythmia, and seizures.

The most common acute complication of sickle cell disease; sickled RBCs obstruct microvascular blood flow causing ischaemic pain (bones, chest, abdomen); managed with hydration, analgesia, and oxygen; triggers include dehydration, infection, cold exposure, and hypoxia.

The period from 4–6 months onward when breast milk alone is insufficient to meet an infant's growing iron demands; iron-rich complementary foods must be introduced by 6 months to bridge this gap and prevent IDA.

A component of Anaemia Mukt Bharat providing 45 mg elemental iron + 400 µg folic acid weekly to school children aged 5–10 years and 60 mg + 400 µg to adolescents 10–19 years; administered on fixed weekdays in schools.