Primary and isolated anaplastic large cell lymphoma of the bone marrow.

Anaplastic large cell lymphoma (ALCL) is a T-cell lymphoma in which the majority of patients present with advanced stage III or IV disease. Here we report a case of ALCL where bone marrow was the only site of disease, in a 60-year-old man with pyrexia and pancytopenia. The diagnosis of ALCL was made on detection of CD30-positive anaplastic cells in the bone marrow, together with prominent hemophagocytosis. Genetics confirmed the clonal nature of the disease and showed it to be anaplastic lymphoma kinase (ALK) negative. Primary isolated bone marrow ALCL should be considered in the diagnosis of pancytopenia associated with hemophagocytosis.