Haematology — 5-min cram sheet

Haematology — 5-min cram sheet

_Built from the haem disease index. Deck-faithful._

Buzzword → answer (the vignette reflex)

• Microspherocytes (no central pallor) + Coombs-negative → hereditary spherocytosis (Coombs-negative separates it from AIHA; osmotic fragility ↑)
• Elliptical / oval red cells → hereditary elliptocytosis (the "milder cousin" of HS)
• Bite cells + Heinz bodies → G6PD deficiency (X-linked; triggers = fava beans, mothballs/naphthalene, oxidant drugs)
• Poikilocytosis + autohaemolysis NOT corrected by glucose → pyruvate kinase deficiency (raised 2,3-DPG → mild symptoms despite low Hb)
• HbH inclusion bodies ("golf-ball" cells) on reticulocyte prep → HbH disease (3-gene α-thal); Hb Barts / hydrops fetalis → 4-gene α deletion
• Sickle cells (target cells prominent in HbSC) → sickle cell disease
• Auer rods → AML (pathognomonic myeloblast; never ALL); MPO / Sudan Black + = myeloid lineage
• Gum hypertrophy / chloromas (oral lesions) → AML M4/M5 (monocytic)
• TdT+ (& PAS+) blasts, no Auer rods → ALL; mediastinal/thymic mass in an adolescent male → T-ALL (presents as lymphoma, airway emergency)
• Smudge / smear cells → CLL
• Aquagenic pruritus (itch after hot shower) → polycythaemia vera
• Teardrop cells + leucoerythroblastic film + massive spleen → primary myelofibrosis
• Reed-Sternberg "owl-eye" (bi/multinucleated) → Hodgkin; popcorn (L&H) cells → NLPHL; collagen bands + lacunar cells → nodular sclerosis (commonest HL)
• Pautrier microabscesses + cerebriform nuclei + epidermotropism → mycosis fungoides (signature triad); leukaemic spread = Sézary
• Tingible-body macrophages ("starry sky") → reactive node — absent in follicular lymphoma; gastric MALToma → H. pylori
• Rouleaux + punched-out lytic lesions / "pepper-pot" skull → myeloma (radio-isotope bone scan false-negative); Bence Jones protein = urinary free light chains
• Congo red → apple-green birefringence under polarised light → amyloid (pathognomonic); β-γ bridging (polyclonal, high IgA) → cirrhosis
• Pancytopenia + hypocellular ("empty") marrow → aplastic anaemia; "Fanconi thumbs" (absent/hypoplastic) → Fanconi anaemia
• Cytopenias + HYPERcellular marrow, ring sideroblasts / Pelger-Huët → MDS ("pre-leukaemia" → AML)
• Howell-Jolly bodies → hyposplenism / post-splenectomy; atypical lymphocytes (abundant cytoplasm) → infectious mononucleosis (EBV)

Genetics / translocations → disease → hook

MPN split: BCR-ABL⁺ = CML; BCR-ABL⁻ classic = PV/ET/PMF (non-classic = mastocytosis, chronic neutrophilic/eosinophilic leukaemia). Almost everything (PV, ET, PMF, MDS) can transform → AML.

Criteria / staging / scores at a glance

• Ann Arbor (lymphoma): I = one node region (or single extranodal, IE) → II = ≥2 regions same side of diaphragm → III = both sides → IV = disseminated extranodal (e.g. marrow). A = no symptoms; B = fever + drenching night sweats + weight loss >10% in 6 months; X (bulky) = >⅓ mediastinal widening OR nodal mass >10 cm; E = single contiguous extranodal site
• Rai (CLL): 0 = lymphocytosis only → 1 = + nodes → 2 = + organomegaly → 3 = + anaemia (Hb <11) → 4 = + thrombocytopenia (Plt <100k). Stages 3–4 = high risk
• Binet (CLL): A = Hb ≥10, Plt ≥100k, <3 areas; B = same bloods, ≥3 areas; C = Hb <10 and/or Plt <100k. (5 areas = neck, axilla, groin, spleen, liver; C ≈ Rai III/IV)
• Active myeloma = CRAB + SLiM. CRAB: C hypercalcaemia (>11 mg/dL or >1 above ULN), R renal (CrCl <40 mL/min or Cr >2 mg/dL), A anaemia (Hb <100 g/L or >20 below LLN), B ≥1 osteolytic bone lesion. SLiM: Sixty = clonal BM plasma cells ≥60%; Light chains = involved:uninvolved FLC ratio ≥100; MRI = >1 focal lesion
• MGUS vs smouldering vs active: MGUS = M-protein <30 g/L & plasma cells <10% & no CRAB; smouldering = >30 g/L & >10% & no CRAB; active = plasma cells ≥10% (or plasmacytoma) + CRAB/SLiM present
• ISS / R-ISS (myeloma): ISS = albumin + β2-microglobulin (tumour burden). R-ISS adds LDH + genetics: I = ISS I + normal LDH + no high-risk genetics (6–7 y); III = ISS III + (high LDH OR high-risk genetics) (<2–3 y). High-risk genetics = t(4;14), t(14;16), del(17p)
• FAB AML (M0–M7): M0 no maturation → M1 minimal → M2 with maturation → M3 = APL (DIC, ATRA) → M4 myelomonocytic → M5 monocytic (gum hypertrophy) → M6 erythroid → M7 megakaryoblastic
• IPSS (MDS prognosis): number of cytopenias + number of marrow blasts + cytogenetic abnormalities
• α-thalassaemia genotypes: −α/αα (1 gene) = silent carrier; −−/αα or −α/−α (2) = α-trait (microcytosis); −−/−α (3) = HbH disease (β₄ tetramers, haemolysis); −−/−− (4) = Hb Barts/hydrops (incompatible with life). α defects = deletions → MLPA/multiplex PCR
• β-thalassaemia genotypes: β/β⁺ or β/β⁰ = trait (minor); β⁰/β⁰ or β⁺/β⁺ = major. β defects = point mutations → β-globin sequencing; two carriers → 25% chance of a major child
• IDA vs β-thal trait: RBC count IDA <5.0 ×10⁶/µL (low) vs β-thal >5.0 (relatively high); RDW elevated IDA vs ≤14% β-thal; HbA2 normal/low IDA vs raised (>3.5%) β-thal
• Iron chelation (thalassaemia): deferoxamine (SC/IV, 30–60 mg/kg, poor compliance); deferasirox (oral OD, 20 mg/kg, hold if ferritin <500 µg/L); deferiprone (oral, cardiac, risk neutropenia/agranulocytosis → weekly CBC). Start after 10–20 transfusions OR ferritin ≥1000 µg/L OR age 3
• Amyloidosis classification: AL = paraproteinaemia/primary/myeloma; AA = chronic inflammation/infection or Familial Mediterranean Fever; ASc = senile/cardiac; PA = neuropathy. Dx = Congo red → apple-green birefringence
• Acute vs chronic leukaemia: acute = blasts (immature), sudden onset, all ages, mild–severe cytopenias, mild organomegaly; chronic = mature cells, insidious, adults, WBC increased, organomegaly prominent

Discriminators that decide questions

1. Micro + high RBC → β-thal trait; micro + low RBC → IDA (RBC is high in thal). β-thal trait also has RDW ≤14% and HbA2 >3.5%; IDA has elevated RDW and normal/low HbA2.
2. Low EPO + JAK2 → primary polycythaemia (PV); high EPO → secondary polycythaemia.
3. Reactive vs neoplastic node: reactive = polyclonal (CD3+/CD20+ mixed), tingible-body macrophages present; neoplastic = monoclonal (light-chain restriction). CD45(LCA)+ = lymphoma; CD45− node mass = metastasis. CD3+/CD20− = T-cell lymphoma; CD3−/CD20+ = B-cell lymphoma.
4. Auer rods AML vs TdT+ ALL: Auer rods + MPO/Sudan Black+ = AML; TdT+ & PAS+, no Auer rods = ALL (B-ALL = CD20+TdT, T-ALL = CD3+TdT).
5. Aplastic anaemia vs MDS (both cause cytopenias): aplastic = hypocellular "empty" marrow (fat-replaced); MDS = hypercellular / ineffective marrow with dysplasia → pre-leukaemia.
6. Sickle aplastic vs sequestration crisis (both = sudden severe anaemia): aplastic (parvovirus B19 kills erythroid precursors) → LOW reticulocytes; sequestration (organ pooling) → HIGH reticulocytes. And CD5+CD23+ B-cell = CLL; persistent lymphocytosis in a patient >60 = CLL until proven otherwise.