Melanonychia Clinical Presentation

Updated: Oct 06, 2020
  • Author: Chris G Adigun, MD, FAAD; Chief Editor: William D James, MD  more...
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Most melanonychia patients present with a history of asymptomatic hyperpigmentation of the nail plate.

A careful history should include information on medications, past treatments, hobbies, illnesses, family history, any history of trauma to the area, prior history of a biopsy of the nail unit, number of nails affected, results of any prior nail clippings sent for histologic examination, results of cultures sent for infectious organisms, change of appearance of the band (or bands) over time, and ethnic background. [21]

In cases of subungual melanoma, the patient may describe a long-standing history of longitudinal melanonychia that recently changed in appearance. Changes that warrant concern include alteration of color, pattern, or size of the band; new onset of pain or ulceration in the site of longitudinal melanonychia; [22] or the presence of subungual blood. [23]


Physical Examination

Melanonychia is characterized by a tan, brown, or black discoloration of the nail unit and is often observed in the nail plate. The nail plate may be diffusely involved, or only a single longitudinal band may be present. Transverse melanonychia has also been rarely reported. One or more digits may be involved.

Levit et al identified characteristics of melanonychia that should warrant concern for subungual melanoma, and they used the acronym ABCDEF to describe them, as follows [24] :

  • (A) Age: The peak incidence in the fifth to seventh decade of life. Additionally, subungual melanoma accounts for one third of melanoma cases in Asians, African Americans, and Native Americans.

  • (B) Brown-black band with breadth greater than 3 mm with variegated borders

  • (C) Change in nail band morphology despite treatment

  • (D) Digit involved: The thumb is more likely to be affected by subungual melanoma than the great toe; the great toe is more likely than the index finger to be affected by subungual melanoma.

  • (E) Extension of the brown-black pigment of the nail bed, nail matrix, and/or nail plate onto the adjacent cuticle and proximal and/or lateral nail folds (Hutchinson sign)

  • (F) Family or personal history of dysplastic nevus or melanoma

Careful examination of the oral and genital mucosa may provide important diagnostic clues to identify Peutz-Jeghers syndrome or Laugier-Hunziker syndrome. [11, 25]