SkinCancerNet Article
Hidden Melanomas

While melanoma usually develops on the skin, it occasionally occurs on other parts of the body, such as the mouth, eye, and inside of the nose. Such melanomas are called "hidden melanomas" because they occur in places not easily examined or not thought necessary to examine.

Fortunately, hidden melanomas are relatively uncommon; however, they are worth knowing about because treatment is most effective in the early stages. Hidden melanomas tend to develop in four areas:

• Nail Bed (underneath the nail)

• Mucosal Tissue (tissue lining the nose, mouth, female genitals,
  anus, urinary tract, and esophagus)

• Scalp

• Eye (eyelid or pigmented coating of the eyeball)

Since hidden melanomas are not easily seen, most are not discovered until they are in an advanced stage. To help you recognize hidden melanomas, the following describes where hidden melanomas occur and possible warning signs.

Nail Bed
Called "subungal (under a nail) melanoma" by dermatologists, this form accounts for about 2% of melanomas in white-skinned individuals and 30% to 40% of melanomas in non-whites. It occurs with equal frequency in males and females, appears most often in people over 50 years of age but can develop at any age, and is seen most often under the nail of the thumb or great (big) toe.

Signs: The most common early warning sign is the appearance of a brown to black-colored streak underneath the nail, which is often mistaken for a bruise. Patients often recall a recent injury to the area, such as stubbing a toe or smashing a thumb, and believe the discoloration is an under-the-nail bruise. For this reason, a physician is usually not consulted. Another reason people delay seeing a doctor is that nail streaks frequently occur in people with dark skin.

Anyone who sees the following underneath a nail, regardless of race, should be seen by a dermatologist as soon as possible:

• Black streak

• Very wide or variegated brown streak

• Nail bed is elevated or has separated from nail bed

• Skin next to the nail becomes darker (more advanced stage)

• Nail looks deformed or as if it is being destroyed (more advanced stage)

Subungal melanoma should be suspected whenever: 1) a nail streak appears without known injury to the nail, 2) the nail discoloration does not gradually disappear as would a bruise, or 3) the size of the nail streak increases over time.

Diagnosis and Treatment: Biopsy (surgical removal of all or part of the lesion) is the only way to diagnosis melanoma with 100% certainty. In the early stages, treatment consists of surgically removing the melanoma. More advanced melanoma may require amputation of the affected finger or toe along with possible removal of the regional lymph nodes and chemotherapy.

Mucosal Tissue
Primary melanomas can arise in mucosal tissue lining the nose, mouth, female genitalia, anus, urinary tract, and esophagus. While these melanomas are relatively rare, they tend to be well advanced when diagnosed — probably because the mucosal tissues are "out-of-sight and out-of-mind" and infrequently self-examined or impossible to examine easily.

Nose and mouth (signs): The most common places for primary (where cancer first occurs) mucosal melanomas to develop are the nose and mouth. Treatment is often delayed because the early signs and symptoms are minor and often ignored or misinterpreted. Signs and symptoms are:

• Nose - Nosebleeds and nasal stuffiness, which may be misinterpreted as "sinus trouble"

• Mouth - A pigmented mass and pain on swallowing, which may be misinterpreted as a canker sore or sore throat. By the time melanoma causes pain, it is probably quite advanced; however, an annual oral examination by a physician may detect melanoma in the mouth before it is well advanced.

• Mouth/nasal cavities (nasopharyngeal) - Inflammation of the inner ear (otitis media), which may be misinterpreted as an ear infection.

Female genitals (signs): A very small percentage of melanomas occur in the female genitals. When it does occur, melanoma develops on the vulva and/or vagina. These melanomas are usually detected during a gynecologic examination. The most common signs and symptoms are:

• Discharge

• Bleeding

• Itching

• Pain

When melanoma arises on the vulva, it occurs on the labia minora, labia majora, or clitoris, and may extend into the vagina. The most common signs and symptoms are vaginal discharge, pain, bleeding, and itching, which may be mistaken for vaginal infection or menstrual irregularity. Most patients with advanced melanomas feel pain and have a recognized change in size, shape, or color of a mole on the vulva.

Vaginal melanoma that does not begin as vulvar melanoma is very rare. When in its early stages, vaginal melanoma does not exhibit signs or symptoms. The common signs and symptoms of advanced disease are vaginal bleeding, foul odor, discharge, and vaginal pain. Most advanced lesions cause symptoms and are diagnosed during a gynecologic examination.

Anus (signs): This type of melanoma is referred to in medical terminology as “anorectal (pertaining to both the anus and rectum) melanoma.” Early lesions usually cause no symptoms. In advanced cases, signs and symptoms may include:

• Rectal bleeding (most common symptom of advanced anorectal melanoma)

• Painful rectal mass (may be mistaken as a hemorrhoid)

Urinary Tract (signs): Melanoma of the urinary tract occurs in both males and females. In the early stages, symptoms are not present. In advanced urethral melanoma, the signs and symptoms are:

• Blood in the urine

• Painful urination

• Frequent urination

• Strained attempts to urinate with little urine passed

Esophagus (signs): Melanoma that first occurs in the esophagus is extremely rare. In the early stages, there are no symptoms. Signs and symptoms of advanced tumors include:

• Difficulty swallowing

• Regurgitation

• Pain

• Esophageal bleeding

Treatment: Surgery is the preferred initial treatment for melanoma of the mucous membranes. In advanced cases, a lymph node biopsy (surgical removal and microscopic examination of one or more lymph node nearest the tumor) and chemotherapy may be necessary.

Scalp
Melanoma that develops on the scalp is considered hidden because the lesion can be easily hidden by hair and the scalp is difficult to self-examine. Symptoms are usually not present until the melanoma is well advanced, so it is very important to examine the scalp during self-examinations for signs of melanoma. Systematically parting the hair with a blow dryer can help.

Signs and symptoms of advanced melanoma on the scalp include:

• Pigmented lesion that has recently appeared or changed

• Lesion follows the ABCDs of Melanoma Detection - Asymmetrical, border irregular, color varies, and diameter greater than 6 millimeters. While melanomas are usually greater than 6 millimeters (size of a pencil eraser) when diagnosed, they can be smaller. If you notice a mole different from others, or which changes, itches or bleeds even if it is smaller than 6 millimeters, you should see a dermatologist.

• Lesion bleeds

Treatment: The lesion is surgically removed, and one or more lymph nodes in the neck may be removed to determine the cancer’s stage. With thicker lesions, there is a possibility of melanoma spreading to nearby lymph nodes in the neck as well as the lungs, liver, and brain.

Eye
Melanoma can develop in the lining of the eyelid (conjunctiva) or the thin pigmented coating within the eyeball (choroids). Signs and symptoms include:

• A feeling of “scratchiness” under the eyelid

• A dark spot on the eyeball

Melanoma of the eye may first be spotted during an eye examination. Due to the potential of the cancer to spread, early diagnosis and treatment are essential. Anyone with suspected ocular melanoma should see an ophthalmologist without delay. Discussion of diagnosis and treatment of ocular melanoma is beyond the scope of this article.

Early Detection Possible
It is possible to detect a hidden melanoma in its earliest stage. During self-examination, the "hidden" areas — fingernails and toenails, web spaces between fingers and toes, skin folds in the armpits, and the scalp — should be examined. For those areas that cannot be self-examined, routine gynecologic, ophthalmologic, and dental examinations should include examination for pigmented lesions.

Reference:
Ross MI, Stern SJ. Mucosal melanomas. In: Balch CM et al (Eds). Cutaneous Melanoma, 3rd ed.
St. Louis: Quality Medical Publishing, Inc.; 1998:195-208.

An educational program brought to you by the American Academy of Dermatology.