Microorganisms (May 2024)

Fungal Melanonychia: A Systematic Review

  • Carmen Rodríguez-Cerdeira,
  • Erick Martínez-Herrera,
  • Paulina Nundehui Cortés-López,
  • Estefanía Guzmán-Montijo,
  • Carlos Daniel Sánchez-Cárdenas,
  • Roberto Arenas,
  • Claudia Erika Fuentes-Venado,
  • Diana Carolina Vega-Sánchez,
  • Rodolfo Pinto-Almazán,
  • Members of Mycology Task Force Group of CILAD

DOI
https://doi.org/10.3390/microorganisms12061096
Journal volume & issue
Vol. 12, no. 6
p. 1096

Abstract

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Fungal melanonychia is an uncommon condition, most typically caused by opportunistic melanin-producing pigmented filamentous fungi in the nail plate. In the present study, the clinical characteristics of patients diagnosed with fungal melanonychia were analyzed through a systematic review of cases reported in the literature. The MESH terms used for the search were “melanonychia” AND “fungal” OR “fungi” through four databases: PubMed, SciELO, Google scholar and SCOPUS. After discarding inadequate articles using the exclusion criteria, 33 articles with 133 cases were analyzed, of which 44% were women, 56% were men and the age range was between 9 and 87 years. The majority of cases were reported in Turkey followed by Korea and Italy. Frequent causal agents detected were Trichophyton rubrum as non-dematiaceous in 55% and Neoscytalidium dimidiatum as dematiaceous in 8%. Predisposing factors included nail trauma, migration history, employment and/or outdoor activities. Involvement in a single nail was presented in 45% of the cases, while more than one affected nail was identified in 21%, with a range of 2 to 10 nails. Regarding the clinical classification, 41% evidenced more than one type of melanonychia, 21% corresponded to the longitudinal pattern and 13% was of total diffuse type. Likewise, the usual dermoscopic pattern was multicolor pigmentation. It is concluded that fungal melanonychia is an uncommon variant of onychomycosis and the differential diagnosis is broad, which highlights the complexity of this disease.

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