Blistering rash in an elderly patient.

An 87-year-old man presented with a 6-week history of painful erosions on the left arm and both lower limbs requiring daily wound dressings. Examination showed multiple sharply demarcated, polygonal erosions with a striking geometric configuration. Although the morphology initially suggested traumatic or contact-related injury associated with wound care, direct immunofluorescence of perilesional skin demonstrated linear C3 deposition along the dermoepidermal junction, and serum anti-BP180 antibodies were positive, establishing the diagnosis of bullous pemphigoid. This case highlights that bullous pemphigoid may present predominantly with erosions rather than intact blisters, particularly in older patients undergoing repeated dressings, and emphasizes the importance of direct immunofluorescence when the clinical morphology is atypical.