Atypical tinea corporis with Id reaction: A case report and successful treatment with upadacitinib.

Atypical tinea corporis, characterized by clinical manifestations that resemble other skin disorders, can lead to misdiagnosis and delayed treatment. This 67-year-old male had a seven-month history of pruritic skin lesions resembling subcorneal pustular dermatosis. Dermatological exam and fungal culture confirmed Trichophyton rubrum-induced atypical tinea corporis. After oral itraconazole treatment, he developed symmetrical eczematous lesions (Id reaction) on his extremities. Initial treatment was ineffective, so upadacitinib was administered, resulting in significant improvement at eight weeks. This case highlights atypical tinea presentations, Id reactions, and introduces upadacitinib as a novel treatment option for refractory Id reactions.