DermatopathologyMelanotic macule of nail unit and its clinicopathologic spectrum
Section snippets
Materials and methods
Fifteen lesions of solitary longitudinal melanonychia in patients who presented themselves from September 2002 to March 2003 were studied. All lesions were biopsied using a 3-mm punch; those lesions narrower than 3 mm were excised by this technique. The specimens included nail matrix and nail plate. The tissue obtained was fixed in formalin and embedded in blocks of paraffin. Sections were mounted on glass slides and stained with hematoxylin-eosin. In addition to the hematoxylin-eosin stain,
Results
The clinical and histopathologic data from 15 patients are summarized in Table I. Figs 1, A; 2, A; 3, A; 4, A; and 5, A, illustrate clinical appearance and Figs 1, B; 2, B; 3, B; 4, B; and 5, B, depict the histopathologic findings in cases 1, 3, 5, 11, and 15, respectively.
Discussion
Longitudinal melanonychia is a clinical term used for a brown-black discoloration in the nail plate that extends in a band from proximal nailfold to distal plate. When it occurs as a solitary lesion it poses a diagnostic dilemma. In some instances the discoloration may result from a pigmented substance inherent in blood, fungi, bacteria, or even a drug.4, 5 However, more commonly, it results from melanin produced by melanocytes in the nail matrix, it being seen in 3 conditions: melanotic
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Funding sources: None.
Conflicts of interest: None identified.