Inflammatory bowel disease (IBD) is characterized by recurrent or chronic inflammation of the gastrointestinal tract, which results in increased risk of developing cancer. Anorectal malignant melanoma is often misdiagnosed as either hemorrhoids or benign anorectal conditions in inflammatory bowel disease. Therefore, the overall prognosis and survival of IBD are poor. To date, the best treatment strategy remains controversial. Only early diagnosis and complete excision yield survival benefit. Here, we report a 64-year-old woman with ulcerative colitis, who was found to have anal malignant melanoma on routine colonoscopy. The lesion was confined to the mucosa with no distant metastasis. She underwent complete trans-anal excision. There was no recurrence at the four-year follow-up. Physicians should be aware of increased risk of cancer development in IBD patients and remember the importance of meticulous inspection of the anal canal.

KeywordsMalignant melanoma; Ulcerative colitis; Anus; Colonoscopy