Melanoma is commonly considered a form of skin cancer. While it is certainly true that most cases of melanoma occur on the skin, this is a disease that can also occur in parts of the body besides the skin, including the eye, and on the mucosal surfaces of the body. These mucosal surfaces line the sinuses, nasal passages, oral cavity, vagina, anus, and other areas.
Melanoma, no matter where on the body it occurs, starts from normal pigment cells called melanocytes. These melanocytes produce melanin, the vital pigment that protects the skin from damage caused by the sun’s ultraviolet rays. For example, while there are approximately 800 melanocytes per square millimeter in the skin of the abdomen, there are 1,500 melanocytes per square millimeter present within the mucous membranes of the nose and mouth. Like the melanocytes found in the skin, these mucosal melanocytes can become cancerous. These changes result in the development of a type of melanoma called mucosal melanoma.
While melanomas that appears on the skin and mucosal surfaces all start from melanocytes, cutaneous (skin) melanoma and mucosal melanoma differ significantly in their behavior and their basic biology. The risk of developing cutaneous melanoma is linked with a history of sun exposure, particularly during childhood; however, this is not true for mucosal melanoma. Indeed, at this time, no clear history of sun exposures, family history, or other risk factors have been established for this disease.
As with most cases of melanoma, complete removal of the mucosal melanoma through surgery provides the greatest likelihood of a cure. The possibility of completely resecting the disease is greatest when diagnosed early; however, unfortunately, such early diagnosis is difficult due to several reasons. Mucosal melanoma is relatively rare, often neither the patients or physicians suspect that it is mucosal melanoma, and the fact that these tumors cause fairly general symptoms. These symptoms differ depending on where the mucosal melanoma develops, but can include bleeding, rectal discomfort, the development of a rectal mass in cases of anorectal mucosal melanoma, vaginal bleeding, vaginal discharge, the development of pigmented spots in cases of vulvovaginal melanoma, or the development of recurrent nose bleeding in sinonasal mucosal melanoma.
Despite the significant advances that have been made in the understanding of mucosal melanoma, this remains a challenging disease to treat. While the new immunotherapy and targeted therapy treatments have greatly improved outcomes in patients with cutaneous melanoma and can help some patients with advanced mucosal melanoma, they generally do not work as well in mucosal melanoma. To develop more successful treatments, we must support combined efforts between the patients dealing with this disease, the doctors caring for them, and the laboratory and clinical researchers working to develop new treatments for mucosal melanoma. It is through this kind of cooperation that we can increase education and awareness of this rare disease and ultimately identify new, more effective, and potentially curative treatments.