A 62 year-woman was admitted with pain in the chest, lower back and both lower extremities in January 1995. Clinical findings revealed osteolytic lesions and hypercalcemia. She sustained a subtrochanteric fracture of the left femur after a fall. We treated the fracture with an intramedullary nail. Biopsy of the osteolytic lesions around the fracture demonstrated osteitis fibrosa cystica with no surrounding tumor cells. After the operation, we demonstrated positive HTLV-1 antisera and a high level of CD4, CD4/CD8 and CD25. In June, a subcutaneous tumor appeared in the left thigh. The biopsy demonstrated a T-cell lymphoma, and we confirmed a diagnosis of ATL. Serum PTHrP was high and serum intact PTH low, suggesting that the cause of the osteolytic lesions was PTHrP originating from the ATL tumor cells.
