Mucosal Melanoma, from the CureRays guide library.

Mucosal melanoma is a rare melanoma that starts on the moist inner linings of the body — such as the nose, mouth, or anorectal area — rather than the skin; it is not caused by sun, is often found late, and is treated with surgery plus radiation, with immunotherapy for advanced disease.

What it is.

Mucosal melanoma is a rare and aggressive form of melanoma that arises from pigment cells (melanocytes) located not in the skin but in the mucous membranes — the moist inner linings of the body. The most common sites are the lining of the nose and sinuses (sinonasal), the mouth and throat, and the anorectal region, with the female genital tract (vulva and vagina) and other linings also affected. Unlike skin melanoma, it is not caused by sun exposure, and it has a different genetic profile — it less often carries the BRAF mutation common in skin melanoma and more often carries changes in the KIT gene. Because these tumors grow in hidden, hard-to-see places, they tend to be found late, after symptoms like nosebleeds, a dark spot in the mouth, or rectal bleeding appear. Complete surgical removal is the main treatment and the best chance at cure, but the locations make wide margins difficult, so radiation is frequently added to improve local control. When the disease spreads, immunotherapy is the foundation of treatment, with KIT-targeted pills for the subset whose tumors carry that change.

How radiation treats it.

Radiation damages the DNA inside cancer cells so they can no longer divide and survive, while normal cells are better at repairing themselves. Melanoma is relatively resistant to ordinary radiation, but in mucosal melanoma radiation still plays an important role because the tumor's hidden, cramped locations make wide surgical margins difficult. Radiation to the tumor site after surgery lowers the chance of local recurrence, and for sinonasal tumors near the eyes and brain, high-dose particle beams (proton or carbon-ion) at specialized centers can concentrate the dose on the tumor while sparing those delicate structures. Radiation is given as short, painless daily sessions and leaves no radioactivity in your body, so you remain safe to be around family and children.

The ways we can treat it.

Surgery. Complete removal of the tumor is the primary, potentially curative treatment, though the confined locations often limit how wide a margin can be taken.

External-beam / particle radiation. Radiation to the tumor site improves local control after surgery; for sinonasal tumors near the eyes and brain, particle-beam radiation (proton or carbon-ion) at specialized centers can deliver a high dose while sparing those structures.

Definitive radiation (when surgery is too disfiguring). When removing the tumor would cost vital function or appearance, radiation can serve as the main local treatment, sometimes alongside systemic therapy.

Questions we hear often.

Did the sun cause this melanoma? No. Mucosal melanoma starts on the moist inner linings of the body — like the nose, mouth, or anorectal area — which are not exposed to the sun. Unlike skin melanoma, it is not caused by ultraviolet light, and it has a different genetic make-up.

Why is radiation used if melanoma resists it? Melanoma is relatively radiation-resistant, but in mucosal melanoma the tumor sits in tight spaces where surgeons often cannot remove a wide margin of healthy tissue. Radiation to the area after surgery helps control any cells left behind, lowering the chance the cancer returns locally.

Should my tumor be tested for gene changes? Yes. Mucosal melanomas more often carry a KIT gene change than skin melanomas do. If testing finds one, KIT-blocking pills may be an option, especially for advanced disease — so molecular testing is a standard part of the work-up.

This guide is informational only. It is not medical advice — please confirm anything here with your care team.