Abstract

A well-appearing 29-year-old male presented to dermatology clinic with painful bullae that appeared four days earlier, one hour after taking liquid tadalafil. Previously, he experienced similar, self-resolving lesions within hours of consuming over-the-counter honey-based sexual enhancement supplements, which often contain tadalafil. Positive findings on exam of his skin, oral mucosa, and eyes included hyperpigmented patches of the mucosal lips, penis, arms, legs, dorsal hands, and dorsal feet. Targetoid lesions consisting of either a central bulla or dusky patch surrounded by a violaceous to erythematous rim were visible on the arms, legs, dorsal hands, and dorsal feet in a symmetric distribution. Two 4mm punch biopsies were performed on the left upper arm. The first was taken at the edge of a tense bulla for H&E, while the other was obtained from a perilesional site one centimeter away for DIF. H&E revealed a subepidermal bulla with epidermal necrosis, vacuolar interface changes, and rare eosinophils suggestive of bullous erythema multiforme. Scattered cytoid bodies on DIF supported the diagnosis. Other blistering disorders were ruled out with the DIF findings, a negative pemphigoid antibody panel, and negative collagen type VII IgG. Tissue PCR, serum IgG, and serum IgM for HSV 1 and 2 were negative. ANA was also negative. Literature review indicates that this is the first reported case of erythema multiforme triggered by tadalafil. This novel case highlights the importance of a comprehensive medication history including supplements and emphasizes the value of clinicopathologic correlation for accurate diagnosis.