A 59-year-old presented with cholecystitis and hepatomegaly. laboratory tests were remarkable for thrombocytopenia (125 × 109/L), alanine aminotransferase 95 U/L, aspartate aminotransferase 760 U/L, alkaline phosphatase 223 U/L, and lactate dehydrogenase 3755 U/L. A peripheral smear showed morphologically normal red blood cells and large atypical lymphoid cells (panel A and inset). Flow cytometry on bone marrow and blood demonstrated a population of gamma-restricted B cells that were positive for CD19, CD20, and CD22, and coexpressed CD5 and CD10. Histologic sections showed large atypical lymphoid cells within small subserosal vessels of the gallbladder, as well as within hepatic (panel C) and bone marrow sinusoids (panel B). Immunohistochemistry showed strong positivity for CD20, PAX-5, CD5, CD10, and Ki-67. Fluorescent in situ hybridization revealed a distal deletion of BCL6 and 3 to 5 copies of BCL2. Intravascular large B-cell lymphoma is a rare subtype of extranodal large B-ce