Does Melanoma Always Start on the Skin?

Health Writer

Melanoma of the skin, called cutaneous melanoma, is the most common form of melanoma. Noncutaneous, or non-skin melanoma, is much rarer but it is possible for melanoma to develop in other parts of the body. About five percent of all melanomas are noncutaneous.

Types of non-skin melanoma

There are two main types of non-skin melanoma:

Ocular - This type of melanoma begins in the eye and is about 80 percent of non-skin melanomas are ocular. According to M.D. Anderson Cancer Center, about 2,000 people throughout the United States and Canada are diagnosed with ocular melanoma each year.

Mucosal - This type of melanoma develops in the melanocytes within the mucus membranes and can occur in the nasal passage, throat, vagina, vulva, anus or mouth. It is the second most common form of cancer of the vulva.

Melanoma can start in other parts of the body as well. A study completed at the University of Istanbul in Turkey in 2011 identified 216 patients with noncutaneous melanoma to determine outcomes as compared to outcomes of cutaneous (skin) melanoma. Of the participants, 83 had mucosal melanoma, 101 had ocular melanoma and 32 had “unknown primaries,” meaning that the starting point of the cancer was unknown.

Risk factors

One study looked at regions of the United States, paying attention to areas where there was a higher level of UV exposure, such as the southern and coastal states.

They did not find any increase which leads researchers to conclude that exposure to UV rays is not a significant risk factor in these types of cancer.

These types of cancer are found more often in older adults over 50 years old. Those who have been previously diagnosed with melanoma (both skin and non-skin), have a higher risk factor. Some types of ocular melanoma are found more often in people with moles or freckles and anorectal cancer is most common in those with AIDS.

Diagnosis of noncutaneous melanoma

Because these cancers are rare, they are often not found until the cancer is well-developed. They are often found when patients develop localized symptoms, such as visual problems. Ocular melanoma might be discovered during an ophthalmologist examination. Mucosal cancers might be discovered in pelvic exams, dental exams, or physical examinations of the mouth, nasal passages or anus.

Mucosal cancers especially can spread very quickly. That is because there is a high number of lymphatic systems that connect the mucous membranes. Even so, many noncutaneous melanomas are not discovered until they are in an advanced stage.

Warning signs

If you have any of the following warning signs, you should immediately see your physician:

  • Discoloration of your eyes
  • Changes in vision
  • Sores in your mouth that don’t heal
  • New growths
  • Rectal bleed
  • Hemorrhoids that do not heal
  • Vaginal bleeding without a cause

Treatment for noncutaneous melanoma includes surgery, chemotherapy, radiation or a combination of treatments.

More on Melanoma

Four Types of Melanoma

Early Warning Signs of Melanoma

Outsmarting Melanoma

References

Noncutaneous malignant melanoma: a prognostic model from a retrospective multicenter study

Q & A: Non-Skin Melanomas

What is melanoma?