The FP gave the patient a diagnosis of benign longitudinal melanonychia. LM may involve one or several digits, and the pigmented bands may vary in color (from light brown to black), vary in width (most range from 2–4 mm), and have sharp or blurred borders.
Extension of pigmentation to the skin adjacent to the nail plate involving the nail folds or the fingertip is called Hutchinson's sign, and is an important indicator for nail melanoma. A biopsy should be performed in an adult if the cause of longitudinal melanonychia is suspicious for melanoma.
The patient described here did not have Hutchinson’s sign. In fact, this case of LM was of an ethnic/genetic origin, as multiple pigmented bands of the nails are common in dark-skinned individuals.
Text for Photo Rounds Friday courtesy of Richard P. Usatine, MD. Photo courtesy of EJ Mayeaux, MD. This case was adapted from: Mayeaux EJ. Normal nail variants. In: Usatine R, Smith M, Mayeaux EJ, et al, eds. The Color Atlas of Family Medicine. New York, NY: McGraw-Hill; 2009:819-821.
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