Anorectal melanoma: a rare aggressive type of melanoma

First described in 1857, anorectal melanoma (AM) is an extremely rare cancer comprising approximately 1% of all anorectal malignancies and cutaneous melanomas. Different from cutaneous melanoma which has a strong association with ultraviolet radiations and a preference for young Caucasians, AM is equally distributed among human races reaching a peak incidence in the eighth decade of life (50%); however, its incidence is increasing in young human immunodeficiency virus and human papillomavirus patients, suggesting a role of immunology for its development.