Malignant Melanoma, Anus
Anal melanoma is a rare and aggressive mucosal melanocytic malignancy, first described by Moore in 1857.
It constitutes 0.5–2% of all anal malignancies and represents less than 2% of all melanomas. The anus is the third most common site for melanoma after the skin and the eye and is the most common site for primary gastrointestinal melanoma.
Patients usually present with anal bleeding (the most common complaints in 50–90% of patients), anal or perianal mass (30%) or anal pain (10%); they can also complain of tenesmus, change in bowel habits, diarrhea, constipation, or incontinence. If a metastatic disease is present, symptoms may include weight loss, anemia, fatigue, groin masses, or bowel obstruction. The average time between the occurrence of symptoms and a confirmed diagnosis is 5–6 months, because patients tend to delay presentation to their doctors, they cannot see asymptomatic lesions and symptoms of anal melanoma are commonly misdiagnosed as...