Abstract We describe a case of unclassifiable T/NK‐cell lymphoma with concomitant acute myeloid leukemia (AML). A 73‐year‐old Japanese man was diagnosed with AML by bone marrow smear, but the presence of splenomegaly and liver tumor was incompatible with AML. Splenectomy and hepatic resection were performed to resolve the thrombocytopenia and define the diagnosis. The pathological findings showed sinusoidal involvement of abnormal lymphoid cells that were CD3‐positive but negative for T‐cell receptor (TCR) rearrangement. Our case could not be categorized as hepatosplenic T‐cell lymphoma because of the lack of immunohistological expression of TCR, despite the clinical similarity.
