Aberrant expression of CD19 and CD43 in a patient with therapy-related acute myeloid leukemia and a history of mantle cell lymphoma.

Mantle cell lymphoma (MCL) is an aggressive B cell lymphoma with frequent involvement of the gastrointestinal tract and peripheral blood (PB). In addition to the B cell markers, the neoplastic cells express CD5 and CD43. In patients with a prior history of MCL with PB involvement, the appearance of leukemic cells after chemotherapy usually heralds a relapse, particularly if the leukemic cells express B cell markers and CD43. We report a patient with MCL who presented with multiple lymphomatous polyposis of the intestine. The staging procedures revealed the involvement of lymph nodes, bone marrow and PB. Three years after chemotherapy, thrombocytopenia with the appearance of rare leukemic cells in the PB was noted. Leukemic cells obtained from bone marrow aspirate expressed CD19 and CD43, suggesting a relapse. Detailed cytomorphological and immunophenotypic studies unveiled the myeloid nature of these leukemic cells, and a diagnosis of therapyrelated acute myeloid leukemia was made. This case illustrates the importance of morphologic examination and performing a complete antibody panel in the diagnosis of a suspected relapse in patients with a prior history of lymphoma.