Primary Liposarcoma of Bone in an Adolescent

We report the clinicopathologic and cytogenetic findings in an unusual case of primary liposarcoma of bone. A 16-year-old girl presented with a destructive, osteolytic tumor of the proximal humerus. Upon biopsy, the tumor was highly anaplastic and necrotizing and was initially considered to be consistent with osteosarcoma. Following chemotherapy, there was 100% tumor necrosis in the resection specimen. Twentyeight months later, solitary supraclavicular and pulmonary metastases appeared with the morphologic features of pleomorphic liposarcoma. Retrospective review of the bone biopsy showed scattered lipoblasts and no unequivocal malignant osteoid. Ghost-like remnants of necrotic liposarcoma were seen in the resection specimen. Cytogenetic analysis of a metastatic lesion showed complex karyotypic abnormalities. Awareness of the existence of primary bone sarcomas with lipogenic differentiation expands the differential diagnosis of malignant bone tumors including cases in the pediatric population. This is the first report of cytogenetic findings in this tumor.