Monocytoid B-cell lymphoma of the prostate.

A case of a primary malignant non-Hodgkin's lymphoma of the prostate, with the histological and immunohistochemical features of monocytoid B-cell lymphoma, is presented. The tumor histology was identical to that described in the forms of node-based monocytoid B-cell lymphoma being composed of a dense, monomorphous lymphoid infiltrate with ovoid nuclei and rather abundant, pale cytoplasm. Phenotypic analysis revealed high expression of B markers 4KB5 and L26, and negativity for T-associated antigens. This unusual localization broadens the spectrum of extra-nodal sites of monocytoid B-cell lymphoma.