Nail disorders in skin of color: Approach to onychoscopic diagnosis

Abstract

Onychoscopy provides a better understanding of nail lesions in terms of diagnosis, monitoring of progression and response to treatment. Author have put forward a simplified way to approach to a nail lesion by onychoscopy. Onychoscopy of pigmentary, inflammatory, infections, neoplastic and connective tissue diseases affecting the individual of skin of color are described to construct a basic outline for onychoscopic approach to a nail lesion. Onychoscopy shows homogenous dark band in longitudinal melanocytic nevus (LMN), irregular black pigment with irregular longitudinal lines in melanoma, multi-colored pigmented patches in fungal melanonychia, purplish-black in subungual hematoma, transverse bands in the under surface of plate in true leukonychia, whitish- yellow patches in pseudoleukonychia. In psoriasis, irregular pits, salmon spots are seen whereas in lichen planus onychorrhexis, whitish linear splits and pterygium are observed. Eczema shows pits with lusterless surface. In Darier's disease, characteristic alternate white and red bands are present. Lichen striatus shows longitudinal erythematous bands and ridging. Red dots with white halos are characteristics in warts. Onychomycosis shows 'aurora borealis' pattern and white opaque and friable spots. Bowen's disease shows white scales with red dots. 'Woodworm appearance' and keratotic mass are seen in onychomatricoma and respectively. Squamous cell carcinoma reveals destruction of nail plate and glomus tumor demonstrates pinkish blush. In connective tissue diseases, characteristic changes are present nail fold capillaries. Onychoscopy assists in the analysis and differentiation of many dermatoses which affect nail unit with similar clinical manifestations.