Mucosal melanoma is a rare form of melanoma that develops in the thin, moist lining (mucosa) of body cavities rather than on the skin. It accounts for roughly 1% of all melanomas in white populations, but a significantly higher share in other groups: about 15% of melanomas in Asian and Pacific Islander populations, 9% in Black populations, and 4% in Hispanic populations. Unlike the more common cutaneous melanoma, mucosal melanoma has no established link to sun exposure, which makes it harder to prevent and often harder to detect early.
Where Mucosal Melanoma Develops
Mucosal melanoma tends to form near junctions where moist inner tissue meets skin. The three most common locations are the head and neck region (about 55% of cases), the anorectal area (about 24%), and the vulvovaginal area (about 18%). Within the head and neck, the nasal passages and sinuses are the most frequent sites, followed by the oral cavity. Less commonly, mucosal melanoma can arise in the esophagus, urinary tract, or other internal mucosal surfaces, though these are exceptionally rare.
The location matters because it directly shapes what symptoms appear, how early the cancer is caught, and what treatment options are available. A melanoma inside the nasal cavity, for instance, may go unnoticed far longer than one on the vulva, simply because the tissue is hidden from view.
Why UV Exposure Is Not a Factor
Most people associate melanoma with sun damage, but mucosal melanoma breaks that pattern entirely. The mucosal surfaces where these cancers develop are never exposed to ultraviolet radiation. Research confirms that UV light is not implicated as a risk factor for melanomas on mucosal surfaces, palms, or soles.
Instead, the genetic drivers behind mucosal melanoma differ from those in sun-related skin melanomas. A notable proportion of mucosal melanomas carry mutations in a gene called KIT, which plays a role in cell growth signaling. This is a meaningful distinction because it opens the door to targeted therapies that wouldn’t apply to typical skin melanomas. The exact cause of mucosal melanoma remains unclear, and no strong lifestyle or environmental risk factors have been identified. It occurs across all racial and ethnic groups, and its relative rarity has made it difficult to study in large populations.
Symptoms by Location
Nasal and Sinus (Sinonasal)
The most common early signs of sinonasal mucosal melanoma are repeated nosebleeds from one nostril, a persistent feeling of blockage or congestion on one side, a continuous runny nose, and facial pain. Because these symptoms overlap with allergies, sinus infections, or nasal polyps, they’re easy to dismiss. A nosebleed that keeps coming back from the same nostril, especially without an obvious cause, is worth investigating.
Anorectal
Anorectal mucosal melanoma often mimics far more common conditions. Rectal bleeding, a change in bowel habits, a feeling of incomplete emptying, itching, and a visible or palpable lump near the anus are typical presenting symptoms. Many patients are initially evaluated for hemorrhoids or polyps before the true diagnosis surfaces. Any irregularly shaped or pigmented lesion in the anal area, with or without ulceration, warrants closer evaluation by a specialist experienced in pigmented lesions.
Vulvovaginal
In the vulvovaginal area, symptoms can include a visible dark or discolored spot, bleeding unrelated to menstruation, itching, pain, or a noticeable mass. As with anorectal melanoma, these symptoms can mimic benign conditions, and the diagnosis is often delayed. Not all mucosal melanomas are darkly pigmented. Some are pink, red, or flesh-colored, which makes self-detection even more difficult.
Why It’s Often Diagnosed Late
Mucosal melanoma carries a worse prognosis than cutaneous melanoma, and a major reason is late detection. The mucosa lines internal cavities that aren’t easily visible during routine self-checks. There’s no equivalent of examining a mole on your arm. By the time symptoms become bothersome enough to prompt a visit, the tumor may have already grown substantially or spread to nearby lymph nodes.
The mucosal lining is also richly supplied with blood vessels and lymphatic channels, giving cancer cells relatively easy access to the rest of the body. This biological reality means mucosal melanomas are more likely to metastasize early compared to skin melanomas of similar thickness. Staging systems reflect this: even localized mucosal melanoma of the head and neck is classified as advanced disease (stage III at minimum), because outcomes are poor even without detectable spread at diagnosis.
How It’s Treated
Surgery is the primary treatment when mucosal melanoma is localized. The goal is to remove the tumor with clear margins, meaning no cancer cells at the edges of the removed tissue. Depending on the location, this can range from relatively straightforward to highly complex. A melanoma inside the nasal cavity, for example, may require endoscopic surgery or more extensive procedures that affect breathing, appearance, or both. Anorectal and vulvovaginal melanomas similarly present surgical challenges because of the sensitive anatomy involved.
Radiation therapy is frequently used after surgery for mucosal melanoma, particularly in the head and neck, to reduce the risk of the cancer returning at the original site. This is more common than with skin melanoma, where radiation plays a smaller role.
Immunotherapy has become a central treatment for advanced or metastatic mucosal melanoma, using the same checkpoint inhibitor drugs that have transformed outcomes in skin melanoma. However, response rates tend to be lower for mucosal melanoma than for its cutaneous counterpart, and researchers are still working to understand why.
For patients whose tumors carry KIT mutations, targeted drugs that block the KIT protein are an option. A large pooled analysis found that about 14% of patients with KIT-mutant mucosal melanoma experienced meaningful tumor shrinkage with these treatments, though the benefits were generally short-lived. While this response rate is modest, it can still offer a window of disease control for patients with limited alternatives.
Prognosis and What Affects It
Five-year survival rates for mucosal melanoma are substantially lower than for cutaneous melanoma. Overall, roughly 25% of patients with mucosal melanoma survive five years, compared to over 90% for skin melanoma caught at a localized stage. The gap reflects the combination of late detection, aggressive biology, and the anatomical challenges of achieving complete surgical removal in tight, complex spaces.
Outcomes vary by site. Vulvovaginal mucosal melanomas generally have a somewhat better prognosis than sinonasal or anorectal tumors, partly because they’re more likely to be noticed earlier. Tumor thickness, whether cancer has reached lymph nodes, and the presence of ulceration all influence individual prognosis, just as they do in skin melanoma. The ability to achieve clear surgical margins is one of the strongest predictors of local control and long-term survival.