Anorectal Melanoma: Not All Dark, Bleeding, and Painful Masses are Hemorrhoids

Abstract

Anorectal Melanoma represents less than 1% of all gastrointestinal tumors. They are infrequent, aggressive and with little therapeutic consensus. The prognosis is usually reserved, with a five-year survival rate of less than 20%. The anorectal canal is the most common place where melanomas of the gastrointestinal mucosa appear. Thus, although it represents 0.05 to 4.6% of anorectal lesions, this constitutes the third most common location of melanoma, after the skin and eyes. Generally, their diagnosis is confusing and late, as they require a high index of suspicion; The symptoms are non-specific but they mostly present as dark, bleeding and painful masses, sometimes being confused with benign anorectal processes such as hemorrhoids. This occurred in two clinical cases that we presented in women aged 78 and 59 years with a purplish-black anorectal mass, the first case confused with hemorrhoidal thrombosis and the other with bleeding internal hemorrhoids; therefore, being treated as such in primary medical care centers and delaying their diagnosis by an average of 3 months (Figure A, B and E). Both cases with high clinical suspicion of a malignant process were later confirmed in a specialized unit, where they underwent biopsies and imaging studies. The patients underwent surgery, with subsequent chemo-immunotherapy. The first with abdomino-perineal resection (Figure C) plus inguinal lymphadenectomy (Figure E) and the other with local excision (Figure F). Both neo or adjuvant treatment and type of surgery remain controversial today.