Hepatosplenic gamma/delta T-cell lymphoma in bone marrow - A sinusoidal neoplasm with blastic cytologic features

We report 8 cases of hepatosplenic T-cell lymphoma (HSTCL) involving bone m arrow and correlate histologic findings with disease progression. Immunophe notypic analysis demonstrated mature, aberrant gamma/delta T-cell immunophe notypes. Isochromosome 7q was identified in 4 cases; 1 case showed the t(7: 14)(q34:q13). Seven of 7 cases tested had monoclonal TCR gamma gene rearran gements. The initial diagnostic bone marrow biopsy specimens were hypercell ular with a frequently subtle, predominantly sinusoidal infiltrate of atypi cal small to medium-sized lymphoid cells. In all cases, aspirate smears at diagnosis and in subsequent specimens contained malignant cells that resemb led blasts, some with fine cytoplasmic granules. With progression, the patt ern of HSTCL in bone marrow biopsy specimens became increasingly interstiti al, and the neoplastic cells became larger In aspirate smears, the proporti on of blasts increased. Seven patients died; I was lost to follow-up. Autop sy performed on I patient demonstrated malignant cells within vascular chan nels in all organs sampled, with relatively little tumor formation, resembl ing intravascular lymphoma at these sites. HSTCL often can be recognized in bone marrow by its unique combination of a sinusoidal pattern in core biop sy specimens and blastic cytology in aspirate smears.