Subungual melanoma frequently presents as a pigmented streak in the nail. Nevi can also be present in the nail producing parallel streaks. Dark streaks in the nail, benign, are very common in darker skinned Caucasians including those of Indo-Pakistani decent, as well as Chinese and Japanese. Multiple pigmented streaks are generally not worrisome.
A single pigmented streak, particularly in a fair skinned individual, is of concern. Atypical lesions grow more rapidly than benign nevi, and this is evidenced by non-parallel sides to the pigmented streaks. The most proximal area is wider than the most distal because the lesion has grown. In addition, in dysplastic or malignant lesions the pigment can extend onto the proximal nail fold, Hutchinson's sign. If these features are evident, the nail must be removed and the nail matrix biopsied.
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