Osseous metaplasia in diffuse large B-cell lymphoma of the kidney.

A 57-year-old female with a history of diffuse large B-cell lymphoma (DLBCL) presented with a renal mass. Microscopic analysis of the nephrectomy specimen revealed DLBCL, confirmed by immunohistochemical analysis (CD45, CD20, CD3, pan-keratin) and polymerase chain reaction (PCR). Multiple spicules of metaplastic bone were identified within the tumor mass, but not within the uninvolved kidney parenchyma. No evidence of bone or dystrophic calcification was detected on the pre-nephrectomy computerized tomography (CT) scan. To our knowledge, this is the first incidence of osseous metaplasia occurring within DLBCL. The pathogenesis of osseous metaplasia is briefly discussed.