Mylabris is a genus of cantharidin-producing blister beetles (Coleoptera: Meloidae) widespread in rural Morocco. Cutaneous cantharidin toxicosis is rarely reported in the Maghrebi literature and is frequently misattributed to allergic reactions. We report the first Moroccan case of cutaneous cantharidin toxicosis following skin contact with a colony of Mylabris spp.

A 39-year-old woman was admitted eleven hours after direct skin contact with a colony of Mylabris sp. in a rural area. Bullous lesions appeared at three hours and macroscopic hematuria at four hours. The patient reported pain at the contact sites and dysuria. Examination revealed multiple serous bullae over a diffuse erythematous-oedematous background from shoulder to sacrum. Hemodynamics were stable. Initial laboratory investigations showed no abnormalities. A repeat full blood count performed the following day revealed thrombocytopenia at 125 × 10 ³ /μL. Serum electrolytes were within normal limits. Entomological identification was achieved twenty-four hours after exposure from a photograph taken by the family and confirmed by the entomology department of the ANSES (French agency for Food, Environmental and Occupational Health and Safety). Conservative management included intravenous rehydration, systemic corticosteroids, aseptic debridement, antibiotic prophylaxis, and renal surveillance. Causal attribution reached I4 (very probable) by CCTV v7.2 imputability assessment (Comité de Coordination de la Toxicovigilance (CCTV) et Groupe de travail Qualité et Méthodes, 2013; Bréchet et al., 2025). Outcome was favorable after two weeks.

Mylabris beetles release cantharidin when threatened or crushed. This potent vesicant causes bullous lesions on contact and may trigger renal injury if absorbed systemically. The association of contact zone bullous dermatosis and macroscopic hematuria is a strong diagnostic indicator of cantharidin toxicosis and should prompt conservative emergency management with close renal monitoring. Systematic photographic documentation of the causative insect proved decisive in making the diagnosis and should be routinely practiced.