Mucosal melanomas.

Abstract

Cutaneous malignant melanoma is a common malignancy and has been increasing at an alarming rate in the United States. Sun exposure is a well-known risk factor related to this disease and much is understood regarding the etiology and epidemiology of cutaneous melanomas. In contrast, primary mucosal melanomas represent an extremely rare malignancy and do not have the same risk factors or behavior patterns. They occur in areas that have no sun exposure and solid predisposing risk factors have not been identified, making this disease very difficult to diagnose or screen for. It is usually diagnosed at a later stage and carries a poor prognosis. Identifying the differences between a primary lesion and a metastatic melanoma is often challenging, because of the lack of definitive criteria, both pathologically and clinically. The rich vascular and lymphatic network surrounding these lesions may be responsible for their aggressive behavior and poor prognosis. In addition, the obscure locations where mucosal melanomas occur are an obvious reason why these lesions often go unnoticed until symptoms develop. Recent literature has raised significant questions regarding recommended treatment strategies. Earlier reports advocated radical surgery as the mainstay of therapy; however, local recurrence and survival were unchanged whether radical surgery or local excision was performed, and the most recent data are favoring the conservative approach when appropriate. Unfortunately, a multitude of adjuvant therapies have been tried without any success. Adjuvant radiotherapy plays a role when combined with surgery, particularly in the head and neck region and female genitalia, but this is reserved for nodal and locoregionally advanced disease and has had no effect when used as a prophylactic method. It is difficult to make significant advances in treatment strategies because of the rarity of the disease. As an example, one in 75 persons born in the year 2000 will develop cutaneous melanoma in his lifetime, compared with four cases per ten million people diagnosed with mucosal melanoma per year in the United States. Possible new therapies based on new biologic and immunologic findings may have future promise on being able to impact this disease. Until then, this aggressive tumor continues to have a poor prognosis, and surgical resection continues to be the mainstay of primary therapy.