Original article
Clinicopathologic features of 28 cases of nail matrix nevi (NMNs) in Asians: Comparison between children and adults

https://doi.org/10.1016/j.jaad.2017.08.052Get rights and content

Background

Clinical distinction between nail matrix nevus (NMN) and subungual melanoma (SUM) can be challenging. More precise delineation of the clinicodermoscopic characteristics specific for NMNs is needed.

Objective

We sought to analyze the clinicopathologic features of childhood and adult NMNs and to propose clinicodermoscopic features that can aid in differentiating NMNs from SUM.

Methods

We retrospectively reviewed clinical, dermoscopic, and histologic findings of patients (20 children and 8 adults) in whom NMN was diagnosed between 2012 and 2015.

Results

Except for 2 cases of total melanonychia, the affected nails demonstrated longitudinal melanonychia sharply demarcated from the adjacent nail plate. Melanonychia was wider among children than among adults (P = .002). Nail dystrophy was more frequent in wider lesions (P = .028). Hutchinson's sign was observed in pediatric cases at the hyponychium and/or proximal nailfold cuticles. All hyponychial pigmentations demonstrated a longitudinal brush pigmentation pattern under dermoscopy.

Limitations

This was a retrospective study of Asians in a single center.

Conclusion

Our study is the largest case series to date of biopsy-confirmed NMNs. It highlighted important clinicodermoscopic differences between pediatric and adult NMNs. We propose that in pediatric cases of longitudinal melanonychia presenting as a sharply demarcated pigment band of even width, the presence of Hutchinson's sign with longitudinal brush pigmentation may favor a diagnosis of NMN over SUM.

Section snippets

Materials and methods

After approval from the institutional review board had been received, 28 biopsy-proven NMN cases diagnosed at Samsung Medical Center from 2012 to 2015 were identified and retrospectively reviewed. This is the largest cohort of biopsy-proven NMNs to date. Clinical records and clinical photographs, dermoscopic images, and biopsy specimens were analyzed. Data gathered from electronic medical records included sex, age, age of onset, location of lesion, clinical features (including width of

Patient demographic data and clinical features

We retrospectively reviewed 28 cases of NMNs. There were 16 female and 12 male patients, and the median age of patients was 5.5 years (range, 3 months-70 years). There were 20 pediatric and 8 adult cases, with median ages of 3.5 and 34 years and male-to-female ratios of 7:13 and 5:3, respectively. Fingernails were affected 4.6 times more frequently than toenails, and the thumb nail was the most commonly affected (43%). The average melanonychia width was 3.5 times greater in children than in

Discussion

NMN can occur in both children and adults. According to previous literature, adult-onset nevi in the skin tend to be small and without changes in the surrounding structures, whereas congenital or childhood nevi are often larger and may be accompanied by alterations of surrounding structures, such as hypertrichosis or appendageal hypotrophy.13, 14 An analogous observation was made in our study of nail unit melanocytic nevi in that pediatric NMNs were wider and cases of wide melanonychia

References (19)

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Funding sources: None.

Conflicts of interest: None disclosed.

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© 2017 by the American Academy of Dermatology, Inc.