Monocytoid B-cell lymphoma with a distinctive clinical presentation.

Monocytoid B-cell lymphoma (MBCL) is a recently described non-Hodgkin's lymphoma. Patients with MBCL usually present with localized or generalized lymphadenopathy; peripheral blood and bone marrow involvement is rare. Patients with leukemic manifestations typically have advanced disease with extensive lymph node and bone marrow involvement. We report a distinctively unusual case of MBCL with peripheral blood and splenic involvement at presentation and with no evidence of peripheral lymph node disease. This case emphasizes the fact that malignancies of monocytoid B cells should be viewed as a spectrum of disease that ranges from leukemia to lymphoma. This feature is similar to other low-grade B-cell neoplasms, such as chronic lymphocytic leukemia/small cell lymphoma, lymphocytic type.