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Practical Dermoscopy
DOI: 10.1016/j.adengl.2021.03.008
Open Access
Available online 14 April 2021
Tinea Nigra: Dermoscopic Findings
Dermatoscopia de tinea nigra
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A. Label
Corresponding author
andreslabel@hotmail.com

Corresponding author.
, J.J. Sole, M. Larralde
Servicio de Dermatología, Hospital Alemán, Ciudad Autónoma de Buenos Aires, Argentina
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A 40-year-old patient with no remarkable past history presented with a light brown macule with irregular contours and a diameter of 3cm×4cm on the inner aspect of the right hallux (Figs. 1 and 2). It was asymptomatic and had been present for 6 months.

Figure 1.

A, Brown macule with irregular contours on the inner aspect of the right hallux. B, Higher-magnification image showing a light brown lesion with irregular contours.

(0.06MB).
Figure 2.

A, Parallel ridge pattern and fine peripheral dots. B, Dermoscopic image showing parallel ridge pattern, reticular pattern, and fine peripheral dots.

(0.09MB).
What Is Your Diagnosis?Diagnosis

Tinea nigra.

Comment

Tinea nigra is a superficial mycosis caused by Hortaea werneckii. It is endemic to tropical and subtropical countries and mainly affects children and young adults. Clinically, it presents as a unilateral brown macule with irregular, well-circumscribed contours, predominantly affecting the palmoplantar region. It follows an asymptomatic, chronic course and may be confused with melanocytic lesions.1

The dermoscopic characteristics of tinea nigra were described by Gupta et al.2 in 1997 as “pigmented spicules” forming a reticular pattern; other findings included fine dots and wispy brownish strands not following the ridges or furrows of the skin. These strands and pigmented spicules correspond to pigmented hyphae in the stratum corneum.3

Noguchi et al.2 later described a case of tinea nigra in which dermoscopy showed a parallel ridge pattern similar to that observed in acral melanoma.

Potassium hydroxide examination is thus recommended to confirm the presence of a superficial mycosis when a parallel ridge pattern is observed in a patient with suspected tinea nigra.

In conclusion, dermoscopy is a valuable tool for evaluating pigmented lesions as it significantly increases diagnostic sensitivity and specificity.

Based on the literature and our experience, we recommend potassium hydroxide examination of pigmented acral lesions with a parallel ridge pattern on dermoscopy to confirm the presence of tinea nigra and avoid unnecessary invasive procedures such as biopsy.4

Conflicts of Interest

The authors declare that they have no conflicts of interest.

References
[1]
H. Noguchi, M. Hiruma, Y. Inoue, K. Miyata, M. Tanaka, H. Ihn.
Tinea nigra showing a parallel ridge pattern on dermoscopy.
J Dermatol, 42 (2015), pp. 518-520
[2]
G. Gupta, A. Burden, G. Shankland, M. Fallowfield, M. Richardson.
Tinea nigra secondary to Exophiala werneckii responding to itraconazole.
Br J Dermatol, 137 (1997), pp. 483-484
[3]
G. Nazzaro, A. Ponziani, S. Cavicchini.
Tinea nigra: a diagnostic pitfall.
J Am Acad Dermatol, 75 (2016), pp. e219-e220
[4]
P. Piliouras, S. Allison, C. Rosendahl, P.G. Buettner, D. Weedon.
Dermoscopy improves diagnosis of tinea nigra: a study of 50 cases.
Australas J Dermatol, 52 (2011), pp. 191-194

Please cite this article as: Label A, Sole JJ, Larralde M. Dermatoscopia de tinea nigra. Actas Dermosifiliogr. 2021. https://doi.org/10.1016/j.ad.2019.11.016

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