Dermatopathology
Melanotic macule of nail unit and its clinicopathologic spectrum

https://doi.org/10.1016/j.jaad.2005.11.1098Get rights and content

The clinical and histologic spectrum of melanotic macule of the nail unit is examined and the differences in the clinical appearance of longitudinal melanochychia caused by melanotic macule and by other kinds of proliferations of melanocytes are assessed. We observed that the clinical appearance of the pigmented band was of little help in establishing the underlying basic pathologic process. This underscores the importance of obtaining a biopsy of the nail matrix in patients who present with solitary longitudinal melanonychia.

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

References (9)

There are more references available in the full text version of this article.

Cited by (47)

View all citing articles on Scopus

Funding sources: None.

Conflicts of interest: None identified.

View full text