Erratum: Roche Scientific Poster Display

Abstract

A CASE OF EXTRASKELETAL OSTEOSARCOMA: CYTOLOGIC DIFFERENTIAL DIAGNOSIS OF DYSCOHESIVE PLEOMORPHIC CELLS WITH OSTEOCLAST-TYPE GIANT CELLS Aim Extraskeletal osteosarcoma is a rare high grade sarcoma arising in deep soft tissues. Although amenable to fine needle aspiration cytology (FNAC), its cytologic findings are infrequently presented. A case of giant cell rich extraskeletal osteosarcoma is presented and the cytological differential diagnosis of malignant dyscohesive pleomorphic cells with giant cells is discussed. Case summary A 61-year-old male presented with a mass in the left deltopectoral groove. His past history included level 1 melanoma. Methods FNAC was performed. Subsequently a resection specimen was received for histology. Results FNAC showed a highly cellular aspirate with malignant cells and osteoclast-like giant cells. H&E sections from the resection specimen were consistent with a giant-cell rich extraskeletal osteosarcoma. Discussion The prominent cytologic feature of osteclastic multi-nucleated giant cells set amongst pleomorphic cells in a soft tissue tumour elicits a differential diagnosis including undifferentiated pleomorphic sarcoma with giant cells, pleomorphic leiomyosarcoma, malignant giant cell tumour of soft tissues, extraskeletal osteosarcoma and non-sarcomatous lesions such as melanoma or lymphoma. These entities will be compared and discussed from a cytologic perspective.