Immunoblastic lymphadenopathy. Evolution into a malignant lymphoma with plasmacytoid features.

In the patient described progressive lymphadenopathy, splenomegaly and interstitial pulmonary disease developed two months after the development of immunoblastic lymphadenopathy. Light microscopic examination of a lymph node biopsy specimen suggested a diagnosis of immunoblastic sarcoma. Evolution of this malignant lymphoma into a leukemic phase allowed detailed studies of the malignant cells by electron microscopy, cytochemical staining and immunologic technics. Evidence is presented that this is a case of malignant lymphoma with plasmacytoid and not lymphoid features. Review of the literature on immunoblastic sarcoma suggests that light microscopy and clinical setting are not sufficient to define a homogeneous clinicopathologic disease.