# Atypical presentation of eczematiform dermatophytid secondary to Trichophyton rubrum onychomycosis: a case report and literature review

## TL;DR

A rare case of eczematous skin lesions caused by a fungal infection in the toenails is reported, highlighting the unusual presentation and treatment.

## Contribution

This case report presents a rare instance of dermatophytid caused by Trichophyton rubrum onychomycosis with atypical clinical features.

## Key findings

- The patient's skin lesions were linked to a toenail fungal infection despite negative mycological tests on the skin.
- Treatment with terbinafine and corticosteroids led to progressive healing of the lesions.
- The case emphasizes the diagnostic challenges of dermatophytids caused by Trichophyton rubrum.

## Abstract

Dermatophytids are inflammatory dermatological manifestations, due to immuno-allergic reactions and hypersensitivity to the antigens of a fungal pathogen. We report a rare case of dermatophytid secondary to Trichophyton rubrum onychomycosis, which is unusual due to the causative agent and also given the location and appearance of the lesions. This is a 54-year-old male, with no particular pathological history. He presented with recurrent eczematous and papular skin lesions on both lower limbs for 2 years, associated with neglected toenail onychomycosis, which preceded the skin lesions by 18 months. Biological investigations were unremarkable. Mycological samples were taken from skin lesions and nails of which the mycological examination revealed Trichophyton rubrum onychomycosis for nail samples, while that of the skin rash samples was negative. In view of this picture, which was suggestive of dermatophytid, the patient was prescribed terbinafine with a strong local corticosteroid, and the evolution under treatment was marked by progressive healing of skin lesions. This clinical case highlights an unusual pathology in which the diagnosis is not always obvious and often misknowned by many practitioners.