Dermoscopy as a first step in the diagnosis of onychomycosis

Abstract

Introduction: Over the years, clinical studies have provided new knowledge about the dermoscopic features of the diseases of cutaneous annexes. It seems that dermoscopy has opened a new morphological dimension in the diagnosis and management of hair disorders and onychopathies.

Aim: To identify and describe dermoscopic features of onychomycosis.

Material and methods: A total of 81 consecutive patients with onychomycosis (55 men and 26 women) were prospectively enrolled in the present study. For each patient, all fingernails and toenails were evaluated in clinical and dermoscopic examinations. Mycological tests were performed by potassium hydroxide (KOH) preparation. Mann-Whitney U and χ² tests were used for the statistical analysis, with a significance threshold of p < 0.05.

Results: Dermoscopic examination of the patients' nails revealed the following: jagged proximal edge with spikes of the onycholytic area (51.9%), longitudinal streaks and patches (44.4%), subungual hyperkeratosis (27.2%), brown-black pigmentation (9.9%) and leukonychia (1.2%). Jagged proximal edge, subungual hyperkeratosis and leukonychia were positively associated with the onychomycosis type.

Conclusions: Onychomycosis accounts for up to 50% of all consultations for onychopathies. Fast and effective diagnostic approaches are needed in everyday clinical practice. Dermoscopy can provide immediate and accurate information in the diagnosis of onychomycosis. We suggest that dermoscopy should be taken as a first step toward the diagnosis of onychomycosis.

Keywords: dermoscopy; fungal melanonychia; jagged proximal edge; onychomycosis; ruin appearance.

Figure 1

Longitudinal streaks in distal subungual onychomycosis (20×)

Figure 2

Distal subungual onychomycosis: dermoscopy shows spikes at the proximal margin of the onycholytic area (40×)

Figure 3

Whitish-yellow patches with jagged proximal edge (20×)

Figure 4

Whitish-yellow patches in distal subungual onychomycosis (20×)

Figure 5

A patch extending proximally, which shows involvement of the matrix (20×)

Figure 6

Fungal melanonychia: yellowish-white streaks within the black pigmentation, note the black reverse triangle (red triangle) and superficial transverse striations (20×)

Figure 7

Pigmented distal subungual onychomycosis: multi-coloured pigmentation and jagged proximal border, note the scales on the surface (20×)

Figure 8

Multi-coloured pigmentation (30×)

Figure 9

Fungal melanonychia: dermoscopy shows black pigment aggregates (red circles) within multi-coloured pigmentation (30×)

Figure 10

Total dystrophic onychomycosis: multi-coloured pigmentation and subungual hyperkeratosis. Note the scales on the surface, reflecting a microdystrophic change caused by nail fragility resulting from the presence of the microorganism (20×)

Figure 11

Irregular matt pigmentation and longitudinal striae (20×)

Figure 12

Superficial transverse striations, reverse triangular pattern (20×)

Figure 13

Subungual hyperkeratosis and longitudinal striae (30×)

Figure 14

Longitudinal striae and ruin appearance in the hyperkeratotic area (20×)

Figure 15

Jagged edge with longitudinal streaks, subungual hyperkeratosis (20×)

Figure 16

Subungual hyperkeratosis and jagged proximal edge with longitudinal striae (20×)

Figure 17

Distal free edge dermoscopy shows ruin appearance (40×)

Figure 18

Proximal subungual onychomycosis: dermoscopy shows a linear edged white patch expanding distally (20×)