Supplementary Material for: Therapy-resistant erosions in the genital area of elderly patients - a differential diagnostic challenge: A Case Report

Introduction: Genital erosions occur in many dermatological conditions and can sometimes be difficult to classify, especially in older patients with multiple morbidities.
Case Presentation: We report the case of an eighty-one year old patient with therapy-resistant genital erythema. Under topical antifungal therapy for a suspected diagnosis of Candida intrigue, the scrotal findings continued to progress, accompanied by genital erosions and new erosions on the nose and right knee. With evidence of IgG and C3 deposition on the basement membrane on direct immunofluorescence and subepidermal cleft formation on histology, a diagnosis of bullous pemphigoid with predominant genital involvement was made.
Conclusion: In conclusion, this case study illustrates that skin biopsies should be taken in cases of therapy-resistant erythema with erosions in order to clarify the dignity and ultimately to be able to adapt the treatment. In addition, it is important to examine the entire integument, including the mucous membranes close to the skin, to avoid overlooking ground-breaking findings. Bullous pemphigoid is the most common blistering autoimmune skin disease and occurs mainly in older people. However, the classic picture of bulging blisters is not always present. Bullous pemphigoid may masquerade clinically as pruritic eczema, erythroderma or erosions. Predominant genital involvement has only been described in a few case reports.