Clinical and onychoscopic evaluation of nail changes in patients with erythroderma

Background: Erythroderma is a severe inflammatory dermatosis involving over 90% of the body surface. Nail changes are common and reflect underlying dermatoses, systemic influences, and disease chronicity. However, their detailed characterization, particularly on onychoscopy, remains insufficiently studied. Methods: This cross-sectional study was conducted at a tertiary referral hospital in India over 18 months. Consecutive clinically diagnosed, untreated erythroderma cases (≥4 weeks off therapy) were enrolled. Comprehensive clinical and onychoscopic evaluation of all 20 nails was performed, with correlation of findings to disease etiology, severity, and chronicity. Results: Fifty patients were assessed, comprising 998 nails (498 fingernails, 500 toenails). Nail abnormalities were present in 90.08% of nails. Psoriasis (44%), atopic dermatitis (10%), and idiopathic erythroderma (10%) were leading etiologies. Common clinical findings included ragged cuticles, longitudinal ridging, scaling, pitting, and nail dystrophy. Onychoscopic abnormalities were seen in 86% of fingernails and 94% of toenails, most frequently involving proximal nail fold. Chronic erythroderma showed significantly greater nail plate involvement, whereas acute disease demonstrated vascular changes of hyponychium and nail bed, better visualized on onychoscopy. Nail fold capillaroscopy was attempted in all patients but was often limited by scaling. Conclusion: Nail involvement is highly prevalent in erythroderma. Routine incorporation of onychoscopy enhances detection of subtle etiologic and temporal patterns, supporting refined clinical assessment and diagnostic decision-making.