Acral Lentiginous Melanoma (ALM)

Where ALM Can Develop

Palm or Sole

It usually begins as an irregularly shaped tan, brown, or black spot. Sometimes people may think it was caused by a recent injury in the general area of the pigmented spot.

Mucous Membranes

Mucous membranes are specialized areas of skin that have a unique lining. Some examples are the mouth, nose, external eyes, and genital openings. Early symptoms of melanoma on these sites include nosebleeds, nasal stuffiness, and a pigmented mass inside the mouth. Melanomas also can develop on the mucous membranes of the anus, urinary tract, and female genitalia.

Under a Nail

The first sign may be a “nail streak,” a narrow, dark stripe under the nail. ALM usually develops on the thumb or big toe; however, it can occur under any fingernail or toenail. Not all nail streaks are melanoma; many dark-skinned people may have nail streaks that are completely benign.

  • A new nail streak, not caused by a recent accident or trauma, an enlarging nail streak, a wide or very darkly pigmented streak, or a nail that is separating or lifting up from the nail bed should always be examined by a dermatologist.
  • A sign of more advanced ALM is when the nail streak has pigmentation in the nail fold skin or when the nail plate is destroyed.
  • ALM of the fingers or toes also can develop without an obvious nail streak, particularly the nonpigmented variety. ALM may, for example, look very much like a chronic infection of the nail bed.

Other Things to Know About Acral Lentiginous Melanoma

  • As an ALM tumor increases in size, it usually becomes more irregular in shape and color (although some ALM lesions can be lightly colored or colorless).
  • The surface of the ALM lesion may remain flat, even as the tumor invades deeply into the skin.
  • Thickening ALM on the sole of the foot can make walking painful and be mistaken for a plantar wart.

Be sure to see a dermatologist as soon as possible if you notice:

  • Bruise that does not fade or comes and goes
  • Nail that lifts up or separates from the nail bed
  • New nail streak not associated with recent trauma
  • An enlarging nail streak
  • Wide or very darkly pigmented nail streak
  • Pigmented mass in the mouth
  • Nosebleeds and nasal stuffiness

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