melanonychia; longitudinal melanonychia; melanonychia striata
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Etiology
- subungual melanoma
- physiologic longitudinal melanonychia
- systemic disorders
- trauma
- inflammatory disorders
- fungal infections
- drugs (azidothymidine, minocycline, antimalarials, gold, chemotherapy)
- benign melanocytic hyperplasias
- lentigo
Epidemiology
- prevalence increases with age
- more common in darker pigmented individuals
- ~100% of blacks > 50 years of age
- in the general white population, prevalence is 1.4%
Pathology
- increased production of melanin by melanocytes in nail matrix
Clinical manifestations
- asymptomatic brown or black pigmentation of the nail
- commonly presents as pigmented band arranged lengthwise along the nail
- longitudinal brown lines may extend from tip of nail into the lunula
- typically multiple nails are involved
- a single nail with longitudinal melanonychia suggests an underlying melanocytic lesion (subungual melanoma)[3]
- suspect melanoma when proximal nail fold involved (Hutchinson's sign)
Laboratory
- nail plate clipping for histologic analysis (KOH prep) & appropriate cultures if fungal infection suspected
- nail matrix biopsy if subungual melanoma suspected[3]
Differential diagnosis
- subungual melanoma is the most serious concern
- melanotic macule of the nail unit
- nail matrix nevus
- onychomycosis
- subungual hematoma
* also see brown nails
Management
- refer to dermatology if subungual melanoma suspected
- directed at underlying etiology
- no treatment indicated for benign etiology
More general terms
More specific terms
References
- ↑ 1.0 1.1 Adigun C. James JD et al (images) Melanonychia http://emedicine.medscape.com/article/1375850-overview
- ↑ 2.0 2.1 DermNet NZ: Melanonychia (images) http://www.dermnetnz.org/hair-nails-sweat/melanonychia.html
- ↑ 3.0 3.1 3.2 Medical Knowledge Self Assessment Program (MKSAP) 17, 18. American College of Physicians, Philadelphia 2015, 2018.
Medical Knowledge Self Assessment Program (MKSAP) 20 American College of Physicians, Philadelphia 2025 - ↑ Jefferson J, Rich P. Melanonychia. Dermatol Res Pract. 2012;2012:952186 PMID: https://pubmed.ncbi.nlm.nih.gov/22792094
- ↑ Alessandrini A, Dika E, Starace M, Chessa MA, Piraccini BM. Diagnosis of Melanonychia. Dermatol Clin. 2021 Apr;39(2):255-267. PMID: https://pubmed.ncbi.nlm.nih.gov/33745638 Review.
- ↑ Darmawan CC, Ohn J, Mun JH et al Diagnosis and treatment of nail melanoma: a review of the clinicopathologic, dermoscopic, and genetic characteristics. J Eur Acad Dermatol Venereol. 2022 May;36(5):651-660. PMID: https://pubmed.ncbi.nlm.nih.gov/35098589 Review.