Florid splenic γ/δ T-cell proliferation in patients with splenomegaly and cytopenias: a "high stakes" diagnostic challenge.

Splenic γ/δ T-cell proliferation is rare, and correct diagnosis is critical for adequate clinical management. Two splenectomy cases from patients with splenomegaly and cytopenias were studied by morphological evaluation, extensive immunophenotyping, FISH and molecular studies. The clinicopathologic findings were compared with splenic T γ/δ neoplasia, notably hepatosplenic T-cell lymphoma (HSTL) and T-cell large granular lymphocytic leukemia (TLGL) of the variety T γ/δ. The enlarged spleens showed expanded red pulp with markedly increased γ/δ T cells, which share significant to complete overlapping morphology and immunophenotype with the neoplastic γ/δ T cells in HSTL and γ/δ TLGL. However, they were polyclonal by molecular study and showed no evidence of isochromosome 7q. Splenectomy alone led to long-term clinical remission in both patients. Two florid reactive splenic γ/δ T-cell proliferations mimicking γ/δ T-cell neoplasia were reported for the first time in English literature. Recognition of this exceedingly rare phenomenon is critical in prevention of misdiagnosis with potentially catastrophic consequences.