Stem cell (immunoblastic) lymphoma. A variant of B lymphocytic lymphoma

From a histologic review of cases coded as Hodgkin's disease and reticulum cell sarcoma, 12 cases were selected as examples of stem cell lymphoma in which the preponderant cell has characteristics of the B immunoblast. Clinically, these lesions affect the elderly (average age 57.3 years), disseminate early, and, with a few exceptions, progress rapidly to a fatal termination. Morphologically, the neoplastic stem cells, which have pyroninophilic cytoplasm, form diffuse infiltrates with an admixture of acidophilic cells. As a regional variation, the pattern in these lesions overlaps histologically with that seen in angioimmunoblastic lymphadenopathy. The overlap in patterns is presumptive evidence that the angioimmunoblastic pattern at times may be a precursory expression of the stem cell lymphoma. On the basis of morphologic features, these tumors are interpreted as a variant of B cell lymphomas.