Deep Dermatophytosis Associated With Inherited CARD9 Deficiency: Efficacy of Topical 1% Voriconazole

ABSTRACT Deep dermatophytosis (DD) is a rare, life‐threatening fungal infection associated with autosomal recessive CARD9 deficiency. Management remains challenging, as systemic antifungals often fail to achieve lasting control. A 54‐year‐old man with a 20‐year history of ulcerative skin lesions and confirmed CARD9 deficiency (Q289X/Q289X) presented with extensive involvement of the scalp, face, and thigh. Trichophyton rubrum was identified by culture and ITS sequencing. Initial combination therapy with oral posaconazole and terbinafine led to marked improvement, but the disease relapsed within 1 year. Liposomal amphotericin B was tried but discontinued due to severe toxicity. Addition of topical 1% voriconazole cream to oral posaconazole resulted in near‐complete healing at 3 months, sustained at 9 months. This case illustrates the therapeutic potential of topical voriconazole as an adjunctive therapy to conventional antifungal treatments for refractory DD.