Mediastinal mass with acute leukemia. Myeloblastoma masquerading as lymphoblastic lymphoma.

Acute leukemia of myeloblastic or myelomonocytic type after non-Hodgkin's lymphoma is a recognized complication of radiotherapy or chemotherapy. However, a few reports suggest spontaneous development of, or coexistent, acute myeloblastic or myelomonocytic leukemia in patients with non-Hodgkin's lymphoma, unrelated to therapy. We studied a case initially interpreted as being lymphoblastic lymphoma with spontaneous acute leukemia, but subsequently shown by cytochemical and ultrastructural studies to be myeloblastoma. We reviewed the previously reported cases of non-Hodgkin's lymphoma with spontaneous myeloid leukemia in the light of our findings, and such cases may, in fact, represent myeloblastomas (granulocytic sarcomas) rather than non-Hodgkin's lymphoma.