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Heliotrope Rash — SCE Rheumatology MCQ

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HardMyositisHeliotrope RashSCE Rheumatology

A patient with longstanding seropositive RA has neutrophils 0.6 ×10⁹/L, splenomegaly and recurrent infections. Blood film shows a persistent CD3-positive large-granular-lymphocyte expansion. Which test most directly distinguishes T-LGL leukaemia from a reactive/Felty-associated expansion?

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Correct answer: D — Flow phenotyping with T-cell-receptor clonality analysis

Explanation lettering: E = shown as A · A = shown as E

D is correct. Felty syndrome and T-LGL leukaemia overlap clinically in RA with neutropenia and splenomegaly. A persistent cytotoxic LGL population requires flow phenotyping and demonstration of T-cell clonality by receptor phenotyping or gene-rearrangement analysis; clonality supports T-LGL rather than a reactive expansion. RF, ANA, bone density and skin histology do not resolve this distinction. Haematology assessment also reviews marrow findings, STAT3 mutations and the duration and absolute count of the clonal population.

Reference: Felty syndrome review: distinction from T-cell large-granular-lymphocyte leukaemia: https://pmc.ncbi.nlm.nih.gov/articles/PMC10619942/