Elsevier

Dermatologic Clinics

Volume 33, Issue 2, April 2015, Pages 185-195
Dermatologic Clinics

Tips for Diagnosis and Treatment of Nail Pigmentation with Practical Algorithm

https://doi.org/10.1016/j.det.2014.12.002Get rights and content

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Key points

  • A brown pigmentation of the nail is not necessarily due to melanin.

  • Dermoscopy should be used routinely when dealing with nail pigmentations.

  • Clinical history, number of nails involved, and associated nail and internal diseases are important parameters to consider when evaluating melanic nail pigmentation.

  • Childhood longitudinal melanonychia of a single digit is most commonly a nevus.

  • Adult-onset melanonychia of a single digit should be carefully evaluated and often needs a bioptic examination.

The

Basic requirements

The visit should be carried out in a well-lit area, provided with a lamp to increase illumination of selected areas. All nails should be examined, even if the patient refers that the discoloration involves one digit. Although it is not easy to convince a patient complaining of fingernail symptoms to show the toenails, they should be examined as well. The fingernails should be looked at with the hands resting on a flat surface and the digits spread, and the toenails should be looked at with the

Step 1: assessment of the nail pigmentation: is the pigmentation due to melanin within the nail or not?

Melanic nail pigmentation is brown or black and within the nail plate, where it forms a linear longitudinal streak or whole nail discoloration, whereas other pigments vary in color and localization.

  • Exogenous pigmentations include different types of colored substances adherent to the nail plate, which becomes partially or totally pigmented (Fig. 2). In exogenous pigmentations, the proximal margin of the discoloration is proximally convex and follows the margin of the nail fold (Fig. 3A).1 Gentle

Step 2: the pigmentation is due to melanin produced by matrix melanocytes (longitudinal melanonychia): how many nails are involved?

Although the literature contains 3 reports of patients with more than one nail involved by melanoma,8, 9, 10 this occurrence is extremely rare and, in general, when longitudinal melanonychia (LM) involves more than one nail, it is due to benign activation of nail matrix melanocytes and should be considered not worrisome.

The most common causes of LM of several nails due to melanocyte activation are as follows11:

  • Racial factors: Up to 80% of African American, 30% of Japanese, and 50% of Hispanic

Step 3: longitudinal melanonychia involves one nail: is it associated with nail lesions that explain its appearance?

Several types of nail diseases may be associated with nail matrix melanocyte activation with appearance of LM: they can be found with clinical history and nail examination and include inflammatory, neoplastic, and traumatic conditions (see earlier in this article for trauma).

  • Among inflammatory nail disorders, both nail psoriasis, especially the pustular variety, and nail lichen planus16 may induce LM due to melanocyte activation. The affected nail typically shows signs of the inflammatory

Step 4: longitudinal melanonychia of one nail, not associated with nail lesions that explain its appearance: is the patient a child or an adult?

This is the most difficult task in the management of LM: dealing with a patient with a pigmented band whose origin cannot be explained by clinical history or examination. The first cutoff derives by age of the patient.

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    Conflicts of Interest to Disclosure: None.

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