Primary adult T-cell leukemia/lymphoma of bone.

A 77-year-old man developed primary adult T-cell leukemia/lymphoma (ATL) of the bone with osteolytic lesions. A biopsy of the lesion revealed proliferation of atypical, large lymphoid cells with a local increase of osteoclasts. The clonal integration of human T-lymphotropic virus type I proviral DNA revealed the tumor cells to be ATL. They produced macrophage inflammatory protein 1alpha (MIP-1alpha) but not parathyroid hormone-related protein or other osteoclast-activating factors. Because MIP-1 produced by tumor cells enhances the expression of receptor activator of nuclear factor kappaB ligand (RANKL) of local osteoblasts and stromal cells, even of tumor cells, the increase of osteoclasts in the close vicinity of ATL cells was considered to result in local bone destruction.