Anaplastic large cell Ki-1 lymphoma: primary bone presentation in an elderly man.

Ki-1 anaplastic large cell lymphoma (Ki-1 ALCL) is a recently recognized entity. Primary presentation in the bone is very rare. Very few cases of primary bone presentation have been reported. All previous reported patients were children and young adults, usually with multiple bone involvement. We report a case of a 60-year old man who presented with extensive mixed blastic and lytic lesions in one tibia, simulating osteogenic sarcoma radiographically, with regional lymphadenopathy. Further studies showed this tumor to be a B cell Ki-1 ALCL. Tumor cells stained positive for Ki-1 antigen (CD30), leukocyte common antigen (CD45), vimentin, and L26 (CD20), negative for cytokeratin, S100, Leu M1 (CD15). The patient was treated with combination chemotherapy and local radiation, with an excellent initial response.