Expect the unexpected - Loss of surface CD3 on flow cytometry in hepatosplenic T-cell lymphoma: An eye opener.

Hepatosplenic T-cell lymphoma (HSTCL) is a rare extranodal T-cell lymphoma that shows preferential sinusoidal infiltration of spleen and liver. It usually shows bright expression of surface CD3 (sCD3) with restriction for γδ-T cell receptors (TCR). We present a case of a 34-year-old male who presented with hepatosplenomegaly and B symptoms. His peripheral blood and bone marrow (BM) was involved by atypical lymphoid cells that were CD2+, CD7+, CD56+, cytoplasmic CD3+, and sCD3- on immunophenotyping by flow cytometry. As sCD3 is a lineage marker for T-cell lymphomas, the loss of sCD3 posed a diagnostic dilemma. However, typical pattern of sinusoidal BM and liver involvement by CD3+ cells and TCR gene rearrangement positivity led to final diagnosis of HSTCL. The differential diagnosis, workup, and clinical course of the case are discussed. To the best of our knowledge, only one case of de novo HSTCL with negative sCD3 has been reported before in the literature.