Most melanomas are hidden by everyday clothing.
Other melanomas are truly "hidden" because they develop on
areas of the skin that are difficult to self-examine or are not usually
considered necessary to self-examine because it is not generally known
that melanoma develops in those areas.
Although these truly "hidden" melanomas
are relatively uncommon in comparison to areas of the body that are seen
more or less every day, they are important to know about because they
are more likely to be discovered at a more advanced stage.
Before, during or after reading this discussion,
you may wish to review criteria for assessing your risk for developing
melanoma and for conducting a whole-body self-examination for melanoma
(Click on Who Is at Risk and Self-Examination
in the Main Menu). Remember that self-examination should include
"hidden" areas such as web spaces between fingers and toes,
genitalia, skin folds in areas such as the armpits and genitalia, and
the hair-bearing scalp. The scalp should be examined by systematically
parting the hair until the entire scalp is examined; a blow-dryer may be
useful in parting the hair. Routine gynecologic, ophthomologic and
dental examinations should include examination for pigmented lesions.
The great majority of melanomas are cutaneous
melanomas—melanomas that develop on the skin. While many cutaneous
melanomas develop on sun-exposed areas of the body, most melanomas
develop on body areas that are under clothing much of the time (torso
and buttocks) or are difficult to self-examine (back, buttocks, backs of
the thighs and legs, scalp, and behind the ears).
Melanomas that might be defined as
"hidden" are those that develop in areas of the body where
they are "out of sight, out of mind": under fingernails and
toenails; in mucous membrane tissue of the nose, mouth, genitalia and
anus; skin of the hairy scalp; ears; on the soles of the feet; and, in
the mucous membranes of the eye. There are also the extremely rare
melanomas that develop as an apparent primary lesion originating in an
internal organ such as the liver, lung, esophagus, gall bladder, middle
ear, brain and intestine.
Subungual (under a nail) melanoma is a rare form
that occurs with about equal frequency in males and females. Its
incidence is about 2 percent of melanomas in whites and up to 30-40
percent of melanomas in non-whites. It can occur at any age; the median
age is 50+ years. It can occur under the nail of any finger or toe, but
occurs most frequently under the nail of a great toe or thumb.
Because the most common sign of an early subungual
melanoma is a brown to black discoloration ("nail streak")
under the nail in the nail bed, the development of melanoma can easily
be mistaken for a subungual hematoma (bruise). The mistaken
identification is often supported by recollection of recent finger or
toe trauma—e.g., stubbing a toe, dropping a weight on a finger or toe,
etc. Mistaking a subungual melanoma for an under-the-nail bruise is a
common reason for delay in seeing a dermatologist or other physician. It
should be noted that nail streaks (pigmented nail matrix nevi) occur
quite commonly in deeply pigmented people and only rarely in
white-skinned people. A lesion suspected of being atypical, or early
melanoma of the nail structure, can include a black streak, very wide
brown streak, or variegated brown streak, regardless of race.
Subungual melanoma can be suspected when (1) a
"nail streak" appears in the absence of recent trauma, (2) the
nail discoloration does not gradually disappear as a hematoma would do,
or (3) it increases in size over time. Pigmentation of the nail fold
(skin next to the nail), or destruction/deformation of the nail plate
are indications of more advanced subungual melanoma.
Suspected subungual melanoma should be examined by
a dermatologist as soon as possible. Biopsy is the only certain method
of diagnosis if a melanoma is suspected. Early melanoma is treated by
surgical excision. More advanced melanoma may require amputation of the
affected finger or toe, investigation and possible removal of regional
lymph nodes, and regional or systemic chemotherapy.
Primary melanomas can arise in mucosal tissue
lining the nose, mouth, esophagus, anus, urinary tract, and female
genitalia. Although mucosal melanomas are relatively rare, they tend to
be well advanced when diagnosed—probably because the mucosal tissues
are "out-of sight, out-of-mind" and infrequently self-examined
or impossible to examine easily (sinus membranes, nasal passages, anus
Mucosal Melanomas of the Nose and Mouth
The nose and mouth are the most common sites of
primary mucosal melanomas (melanomas that originate at those sites).
Treatment is often delayed because early symptoms are minor and often
ignored or misinterpreted:
- Nose—nosebleeds and nasal stuffiness may be
misinterpreted as "sinus trouble"
- Mouth—a pigmented mass and pain on swallowing
may be misinterpreted as a "canker sore" or "sore
throat"; if the melanoma causes pain, it is probably quite
advanced; an annual oral examination by a physician may detect
melanoma in the mouth area before it is well advanced
- Nasopharyngeal—inflammation of the inner ear
(otitis media) may be misinterpreted as an ear infection
Surgery is the preferred initial treatment for
melanoma at these sites.
Mucosal Melanoma of the Female Genital Tract
The genital tract accounts for a small percentage
of melanomas diagnosed in women:
- Vulva—Melanomas can arise on the labia minora,
labia majora, or clitoris, and may extend into the vagina. The most
common symptoms are bleeding and itching that a patient may
mistakenly identity as menstrual irregularity or vaginal infection.
Most patients with advanced melanomas have symptoms and have
recognized a change in size, shape or color of a mole on the vulva.
Most melanomas are discovered by a physician during a gynecologic
examination. Complete surgical excision is the preferred treatment
for melanoma of the vulva.
- Vagina—Vaginal melanoma that is not an
extension of vulvar melanoma is very rare. The common symptoms of
advanced disease are vaginal bleeding, foul odor and discharge, and
vaginal pain. Most advanced lesions cause symptoms and are diagnosed
during gynecologic examination. Complete surgical excision is the
preferred treatment for vaginal melanoma. Early, curable melanomas
of the vagina are usually asymptomatic and are only detected during
examination of these sites.
Anorectal Mucosal Melanoma
Rectal bleeding is the most frequent symptom of
advanced anorectal melanoma and there may be a painful rectal mass that
the patient mistakenly believes to be a hemorrhoid. Early lesions
usually cause no symptoms. An anorectal melanoma may be well advanced
before it is brought to the attention of a physician. Surgical excision
is the treatment for anorectal melanoma. Lymph node biopsy, lymph node
investigation and systemic chemotherapy may be necessary when melanoma
is more advanced.
Mucosal Melanoma of the Urinary Tract
- Males—Melanoma of the penis is more frequent
on penile skin than in mucosal tissue of the urinary tract
(urethra). Symptoms of advanced urethral melanoma are blood in the
urine and painful urination. Most early melanomas of the penile skin
or urethra cause no symptoms.
- Females—Melanoma of the urethra may cause
symptoms of frequent urination, painful urination, or urinary
obstruction. Early lesions usually cause no symptoms.
Mucosal Melanoma of the Esophagus
Primary melanoma of the esophagus is extremely
rare. Symptoms of advanced tumors include difficulty swallowing,
regurgitation, pain, and esophageal bleeding. Early lesions usually
cause no symptoms.
Cutaneous Melanoma of the Hairy Scalp
Cutaneous melanoma of the hairy scalp can be a
"hidden" melanoma because (1) the scalp is difficult or
impossible to self-examine, (2) there may be no symptoms until the
melanoma is well advanced, and (3) the scalp is usually "out of
sight, out of mind." A well-developed cutaneous melanoma of the
hairy scalp is shown in this photo:
A brown-black plaque was present on
the scalp of a 65-year-old woman for several years. Although noted
several times by a family member, it was not regarded as a
"dangerous" lesion. When the lesion became large enough to
cause problems in combing her hair, the woman sought medical attention.
The lesion was diagnosed as superficial spreading melanoma and
(Photo used with permission of the
American Academy of Dermatology National Library of Dermatologic Teaching
Slides and the Sulzberger Institute for Dermatologic Education)
Primary melanoma can develop in the
lining of the eyelids (conjunctiva) or in the thin pigmented coating
within the eyeball (choroid). Conjunctival melanoma may be initially
identified when a patient looks for the cause of
"scratchiness" under the eyelid. Choroidal melanoma is often
noticed first during an ophthalmologic examination for eyeglasses, or
the patient may note a "dark spot" on the eyeball near the
lens. Choroidal melanoma may metastasize, so early diagnosis and
treatment are essential. A person with suspected ocular melanoma should
be seen as soon possible by an ophthalmologist. The management of
patients who have ocular melanoma is beyond the scope of this review
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.