MALIGNANT-MELANOMA OF SOFT PARTS INVOLVING THE HEAD AND NECK REGION -REVIEW OF LITERATURE AND CASE-REPORT

Malignant melanoma of soft parts (MMSP) was originally described as a distinct entity by Enzinger in 1965 and was termed ''clear cell sarcom a of tendons and aponeuroses'' because of its association with tenosyn ovial structures. It has been shown immunophenotypically and ultrastru cturally that this tumor is derived from neuroectoderm and shares a nu mber of features with cutaneous melanoma. Over 95% of MMSPs present in the extremities, with the head and neck region (1.9%) being an unusua l site. This study presents an additional case of MMSP of the head and neck region involving the posterior cervical region in a 15-year-old Hispanic male and reviews the literature on MMSP. Ultrastructural exam ination showed rudimentary cell attachments, smooth cell membranes, di scontinuous basal lamina, scanty glycogen, and occasional premelanosom es in some tumor cells. Cytogenetic analysis showed a reciprocal trans location between the long arms of chromosomes 12 and 22 [t(12:22)(q13; q12.2)], characteristic for MMSP and not seen in cutaneous melanoma. S urvival in MMSP has been correlated with tumor size, tumor necrosis, a nd ploidy status. Overall reported clinical outcome for this tumor is as follows: died of disease, 45%; alive with disease, 23%; no evidence of disease, 30%; and died of other causes, 2%. MMSP represents a dist inct entity with a characteristic ultrastructural appearance and a tum or defining cytogenetic translocation.