CYTODIAGNOSIS OF MALIGNANT-MELANOMA OF SOFT-TISSUE - REPORT OF A CASEWITH DIAGNOSIS BY INTRAOPERATIVE CYTOLOGY

BACKGROUND: Malignant melanoma of soft tissue (MMST) is a rare tumor a nd consists of <1% of all soft tissue neoplasms. There are few reports on its cytodiagnosis. CASE: A 14-year-old male attended the Departmen t of Orthopedics, Juntendo University Urayasu Hospital, in August 1994 because of a painless tumor in the distal portion of the left thigh. Intraoperative imprint smear examination led to a diagnosis of maligna nt melanoma, and wide resection of the tumor, including the surroundin g normal tissue, was performed. On cytologic examination, the backgrou nd was relatively clean, with tumor cells distributing individually or in clusters. Under high magnification, the tumor cells were seen to c ontain a slightly enlarged, conspicuous nucleolus and large cell body. The cells varied in shape from polygonal to spindle shaped, with a fe w multinuclear giant cells. Melanin and glycogen were observed in vary ing degrees in the tumer cells. CONCLUSION: MMST can be diagnosed easi ly if melanin is observed in the cytoplasm. Even in the absence of mel anin, the tumor has relatively characteristic cytomorphology. Intraope rative cytology is useful for an accurate diagnosis of the tumor.