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Felty Syndrome — SCE Rheumatology MCQ

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HardRheumatoid ArthritisFelty SyndromeSCE Rheumatology

A 58-year-old woman with an 18-year history of high-titre rheumatoid factor and anti-CCP-positive erosive rheumatoid arthritis develops recurrent bacterial infections. Her neutrophil count has remained between 0.5 and 0.8 × 10^9/L for 6 months, and examination confirms splenomegaly. Methotrexate was withdrawn 12 weeks ago without improvement. A blood film shows no dysplasia or hairy cells, and bone marrow examination shows no malignant infiltration or myelodysplasia. Peripheral-blood flow cytometry shows no persistent expanded large granular lymphocyte population, and T-cell receptor gene-rearrangement analysis is polyclonal. What is the most likely diagnosis?

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Correct answer: B — Felty syndrome

This is Felty syndrome: persistent otherwise unexplained neutropenia in a patient with long-standing, seropositive, erosive rheumatoid arthritis, commonly accompanied by splenomegaly and recurrent infection. T-large granular lymphocyte disease is the most important mimic because it is associated with RA, neutropenia and splenomegaly; however, there is no expanded LGL population and T-cell receptor testing is polyclonal. Myelodysplastic syndrome would usually be supported by marrow dysplasia, often involving additional cell lines. Hairy cell leukaemia would require a characteristic clonal B-cell infiltrate and compatible blood or marrow morphology. Drug-induced neutropenia is less likely because the count did not recover after adequate withdrawal of methotrexate. The negative exclusion studies therefore make Felty syndrome the single best diagnosis.

Reference: Wegscheider C, Ferincz V, Schöls K, Maieron A. Felty's syndrome. Frontiers in Medicine. 2023;10:1238405. https://pubmed.ncbi.nlm.nih.gov/37920595/