Primary anorectal melanoma: report of 4 cases and literature review

Anal melanoma is a rare aggressive disease, representing 0.4% to 1.6% of all melanomas and 1% of tumors of the anal canal. Its diagnosis is complex and in most cases is made in later stages with diffused disease, which contributes to its poor prognosis. Due to its low incidence, most studies are based on case reports and there is no consensus on the best diagnostic and therapeutic course of treatment. As a rule, the cure rate is low and the expected 5-year survival is 20%. As a consequence, therapy should be individualized, evaluated on a case-by-case basis, aiming locoregional control to provide better quality of life for the patient.