While melanoma cancer develops on skin layers most of the time, mucosal melanomas occur inside your body, specifically in mucous membranes. They are typically more difficult to detect than skin melanoma.

Mucosal melanoma is a subtype of melanoma that first appears in the mucous membranes — or moist surfaces — of your body.

Symptoms will depend on what organs it affects, but it can be harder to diagnose than other melanomas due to being inside your body.

Unlike skin melanomas, mucosal melanoma affects internal organs, mainly those in the gastrointestinal, respiratory, and urogenital tracts.

Mucosal melanoma may develop on your:

  • mouth
  • nose and sinuses
  • throat
  • stomach
  • gallbladder
  • intestines
  • vagina and vulva
  • anus

Mucosal melanomas are not always pigmented or visible, which may make them harder to diagnose during early stages. The common ABCDE rule used to assess skin cancer doesn’t apply either.

The symptoms of mucosal melanoma may also depend on the affected area and may mimic other conditions.

General symptoms of mucosal melanoma per region may include:

Respiratory tract symptoms

  • nasal obstruction
  • throat irritation and soreness
  • voice hoarseness
  • difficulty breathing
  • neck pain
  • palpable masses in the neck
  • cough
  • pigmented or non-pigmented lesions

Gastrointestinal tract symptoms

  • difficulty swallowing
  • unexplained weight loss
  • blood in feces or vomit
  • abdominal pain
  • anemia
  • nausea
  • rectal bleeding
  • pain in the rectal area
  • gallstones
  • dark urine

Urogenital tract symptoms

  • lumps in or around the vulva
  • atypical discharge with itching or irritation
  • pigmented lesions that bleed or hurt
  • blood in the urine
  • painful urination

Many of these symptoms may result from other conditions. Only a healthcare professional can provide an accurate diagnosis by gathering clinical information (signs and symptoms), and personal medical history, and determining if you need specific testing.

The cause of mucosal melanoma is not yet known. It isn’t associated with exposure to ultraviolet rays, like cutaneous melanoma. Instead, some mucosal melanomas have been associated with gene mutations.

Learn more about the causes of skin melanoma.

Some possible contributing factors that could increase someone’s chances of developing mucosal melanoma may include:

  • In the areas in or near the mouth:
    • dentures that don’t fit properly
    • tobacco use
    • exposure to environmental toxins that increase the chance of cancer
  • In the area of the vulva or vagina:
    • viral infections
    • environmental chemical toxins or irritants
    • chronic inflammation
  • In the area of the rectum or anus:
    • HIV

Not everyone with these contributing factors may develop melanoma, but it’s believed they could increase some people’s chances.

The staging guidelines for mucosal melanoma are different from those for cutaneous melanoma, although they follow the same melanoma staging outline based on tumor growth, lymph node involvement, and metastasis.

The American Joint Committee on Cancer (AJCC) Tumour, Node, and Metastasis (TNM) or AJCC-TNM staging system is used to stage mucosal melanoma of the head and neck, as well as the vulva and vagina.

The staging for these mucosal melanoma sites is as follows:

  • T3: Mucosal disease is first recognized and diagnosed.
  • T4A: Moderately advanced mucosal disease now involves cartilage, deep soft tissue, or overlying skin.
  • T4B: Very advanced mucosal disease now involves one or more of the following tissues and structures:
    • brain
    • dura mater (outermost layer of the meninges in the brain)
    • the base of the skull
    • lower cranial nerves controlling the throat and voice box, neck muscles, and tongue
    • masticator muscles (used for chewing)
    • carotid arteries in the neck
    • prevertebral space
    • mediastinal structures, including the food pipe, trachea, heart, blood vessels, and chest lymph nodes

Vaginal and anorectal mucosal melanomas do not yet have a specific staging system. Because of this, a basic clinical stage classification system is typically used:

  • Stage 1: Mucosal melanoma tumors are local.
  • Stage 2: The cancer has spread to lymph nodes in the immediate region or area.
  • Stage 3: The cancer has reached distant organs and regions (metastasis).

Surgical removal of the tumor is the first line of treatment for local mucosal melanoma. However, some tumor locations may make complete removal challenging, which increases the chances of tumor recurrence within 6–12 months.

In many cases, your healthcare team may decide to pair this surgical approach with chemotherapy or radiation therapy (RT) to kill cancer cells that may remain in the area after surgery.

Adjuvant therapies may also include targeted therapy and immunotherapy, which involves the use of certain medications that have been successful in prolonging the lives of people with some types of melanoma.

If the melanoma is nearby or on a vital organ — like the heart — radiation, chemotherapy, or both may be used.

The primary complication of mucosal melanoma is the cancer spreading due to its tendency to progress quicker than other cancers. at the metastasis stage, few treatment options are available and they may focus on palliative care (relieving symptoms and boosting quality of life).

Mucosal melanoma develops in the mucous membranes of the body. It mainly affects the respiratory, gastrointestinal, and urogenital tracts.

Because of the locations being inside the body and not always involving pigmented lesions, mucosal melanoma is often harder to diagnose than melanoma of the skin. This may lead to diagnosis in more advanced stages.