Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Case Reports
. 2021 Jan;7(1):41-45.
doi: 10.1159/000510674. Epub 2020 Oct 5.

Subungual Nail Erythrasma Presenting as Melanonychia: A Rare Finding

Jalal Maghfour  1 , Jennifer Kane  2 , Leslie Robinson-Bostom  2 , John Kawaoka  2 , Nathaniel Jellinek  2
Affiliations
Case Reports

Subungual Nail Erythrasma Presenting as Melanonychia: A Rare Finding

Jalal Maghfour et al. Skin Appendage Disord. 2021 Jan.

Abstract

Nail pathology may reflect a wide array of localized and systemic dermatological conditions. Certain nail findings such as melanonychia can create diagnostic challenges even to nail experts. We report a case of a 78-year-old man who presented with melanonychia of the great toe. Nail clipping showed focal melanin deposition, and dermoscopy demonstrated a region of localized erythema in the lunula concerning for possible melanocytic neoplasm. Subsequent nail biopsy showed numerous vertically oriented filamentous bacteria and coccobacilli within the nail plate consistent with a diagnosis of subungual nail erythrasma. Nail erythrasma is a rare entity. Additionally, this case highlights a new clinical presentation of nail erythrasma as melanonychia.

Keywords: Cornyebacteria; Erythrasma; Nail matrix; Nail plate.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Fig. 1
Fig. 1
a Smudged brown proximal lateral nail plate discoloration. b Residual minimal brown lateral nail plate discoloration, limited to the distal plate, at follow-up visit. c Wood's lamp examination showing coral red fluorescence between the left first and second toe web space. d Wood's lamp examination showing mild fluorescence of the proximal lateral nail plate.
Fig. 2
Fig. 2
Nail bed with attached nail plate showing mild hyperkeratosis and parakeratosis with focus of superficial detachment. a H&E, original magnification ×20. High-power photomicrograph showing numerous vertically oriented filamentous bacteria and coccobacilli within the superficial nail plate. b H&E, original magnification ×100. c H&E, original magnification ×400. Gram stain highlighting numerous vertically oriented filamentous bacteria and coccobacilli within the superficial nail plate. d H&E, original magnification ×400.
See this image and copyright information in PMC

References

    1. Negroni P. [Erythrasma of the nails] Med Cutan Ibero Lat Am. 1976;4((5)):349–57. - PubMed
    1. Duhard E, Calvet C, Mariotte N, Tichet J, Vaillant L. [Prevalence of longitudinal melanonychia in the white population] Ann Dermatol Venereol. 1995;122((9)):586–90. - PubMed
    1. Jellinek N. Nail matrix biopsy of longitudinal melanonychia: diagnostic algorithm including the matrix shave biopsy. J Am Acad Dermatol. 2007;56((5)):803–10. - PubMed
    1. Haneke E, Baran R. Longitudinal melanonychia. Dermatol Surg. 2001;27((6)):580–4. - PubMed
    1. Sommer LL, Reboli AC, Heymann WR. Bacterial diseases. In: Bolognia JL, Schaffer JV, Cerroni L, editors. Dermatology. 4th ed. Vol. 1. Philadelphia: Elsevier; 2018. pp. p.1274–7.

Publication types