Cytodiagnosis of malignant melanoma of soft tissue: report of a case with diagnosis by intraoperative cytology.
BACKGROUND
Malignant melanoma of soft tissue (MMST) is a rare tumor and consists of < 1% of all soft tissue neoplasms. There are few reports on its cytodiagnosis.


METHODS
A 14-year-old male attended the Department 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 malignant melanoma, and wide resection of the tumor, including the surrounding normal tissue, was performed. On cytologic examination, the background was relatively clean, with tumor cells distributing individually or in clusters. Under high magnification, the tumor cells were seen to contain a slightly enlarged, conspicuous nucleolus and large cell body. The cells varied in shape from polygonal to spindle shaped, with a few multinuclear giant cells. Melanin and glycogen were observed in varying degrees in the tumor cells.


CONCLUSIONS
MMST can be diagnosed easily if melanin is observed in the cytoplasm. Even in the absence of melanin, the tumor has relatively characteristic cytomorphology. Intraoperative cytology is useful for an accurate diagnosis of the tumor.
Department of Clinical Laboratory, Juntendo University Urayasu Hospital, Japan.
K
K
Ishi
F
F
Suzuki
A
A
Saito
J
J
Koyatsu
K
K
Kina
K
K
Shitoto
D000293:Adolescent; D005629:Frozen Sections; D006801:Humans; D007432:Intraoperative Period; D008297:Male; D008543:Melanins / Q000032:analysis; D008545:Melanoma / Q000175:diagnosis* / Q000473:pathology* / Q000648:ultrastructure; D012983:Soft Tissue Neoplasms / Q000175:diagnosis* / Q000473:pathology* / Q000648:ultrastructure; D013848:Thigh
D008543:Melanins