Anal malignant melanoma: diagnosis and next steps

It can resemble more familiar anal problems, and some tumours have little visible pigment. Diagnosis depends on examination and a tissue sample rather than appearance alone.

Anal melanoma may present with rectal bleeding, discomfort, a lump, altered bowel habits, discharge or a dark patch near the anus. These symptoms have many possible causes; anal melanoma can present with them, but their presence does not establish cancer.

A specialist examines the anal region and rectum, then arranges biopsy of a suspicious area. A pathologist examines the sample and may use laboratory markers to confirm melanoma. Imaging and lymph-node assessment then help show whether disease is confined to the original site or has spread.

Care is usually coordinated by a team familiar with melanoma and cancers of the anal region. Bring the biopsy report, scan reports and a current medicine list to consultations. The team considers the tumour's location, extent, molecular features, your general health and the effect each option may have on bowel function.

Treatment may involve surgery to remove the tumour, medicines that activate the immune system, targeted medicines when relevant, radiotherapy or a combination. The appropriate sequence is individual, so another patient's plan may not match yours.

Arrange prompt assessment for unexplained or repeated rectal bleeding, a new anal lump, persistent pain, a changing pigmented patch, discharge or a lasting change in bowel habits. Seek urgent help for heavy bleeding, fainting, inability to pass stool or gas, severe worsening pain, fever or marked weakness.

If melanoma is already diagnosed, contact the treating team about new neurological symptoms, breathlessness, jaundice, uncontrolled pain or a rapid decline in function. These changes require evaluation and should not be saved for a routine follow-up visit.

Ask what the biopsy shows, where the melanoma began, what imaging is needed and whether molecular testing could influence treatment. Request a plain-language explanation of the goal of treatment, expected effects on bowel function, side effects that need urgent contact and the follow-up schedule.