P017 Localized penile bullous pemphigoid: a case report

Abstract A 69-year-old man presented with a 3-month history of recurrent, itchy blisters on the penile shaft. Past medical history included ischaemic heart disease and hypertension. Medications included amlodipine, aspirin, atorvastatin, bendroflumethiazide and bisoprolol. Examination revealed discrete, deroofed bullae on a slightly eroded base on the penile shaft, with evidence of postinflammatory pigmentary changes. The penile glans and scrotum were unaffected. The remaining full-skin examination, including oral mucosa, was noncontributory. Histological analysis by punch biopsy showed skin with dermal eosinophils and scattered intraepidermal eosinophils. A rare eosinophil was seen at the base of the epidermis. No definite neutrophils were seen. No bulla was identified. Direct immunofluorescence analysis of perilesional skin showed strong linear C3, linear IgG and patchy linear IgA deposition on the dermoepidermal junction, suggestive of a bullous disease. Serum indirect immunofluorescence was negative for anti-BP180 and anti-BP230 antibodies, with normal full blood count and renal and liver profiles. Clinically, the working diagnosis was a localized bullous pemphigoid (BP), and the patient was prescribed clobetasol propionate ointment topically once daily for 4 weeks and oral doxycycline 100 mg once daily and nicotinamide 500 mg three times daily for 3 months. After 2 weeks the bullae had resolved, with no new bulla development. Two months following treatment initiation the patient remains symptom free, and clinically without disease recurrence and no reported adverse drug event. BP is the most common autoimmune subepidermal blistering skin disease, with autoantibodies targeting BP180 or BP230 proteins. BP usually presents in older patients, with an increased prevalence in those with a history of stroke, Parkinson disease and dementia. Clinical presentation typically describes painful, itchy, tense bullae of the skin, either localized or widespread across the trunk and proximal limbs. Genital BP is a rare subgroup of localized BP, typically affecting women and children. Differential diagnoses for BP include fixed drug eruptions, contact dermatitis, dermatitis herpetiformis, linear IgA disease and infective causes such as bullous tinea. From a literature search, this is the fifth case of BP localized solely to the male genitalia. Dermatologists should consider localized BP in male patients presenting with bullae on the penis with confirmation by skin biopsy and immunofluorescence analysis, to initiate prompt treatment and disease control and avoid significant morbidity for this patient group.