Bullosis diabeticorum: A neglected bullous dermatosis

A 75-year-old African-American man presented with a 3-year history of painless, fluid-filled blisters, for which his primary care physician had treated him with doxycycline, cephalexin, and topical corticosteroids, with no significant improvement. The blisters had ruptured spontaneously and healed with scarring. He denied antecedent trauma. His medical history was remarkable for insulin-dependent type 2 diabetes mellitus, hypertension, hypercholesterolemia, primary cutaneous melanoma status-post excision, and breast cancer status-post mastectomy and chemotherapy. Physical examination revealed nontender bullae, measuring up to 4 cm × 3 cm and containing serous fluid, on the anterior portion of both tibias (Figure 1). The Nikolsky sign was negative. There was no evidence of surrounding inflammation. A biopsy revealed subepidermal bullae formation with sparse inflammatory infiltrate (Figure 2). Direct and indirect immunofluorescence studies were negative for immunoglobulin (Ig) G, IgA, IgM, complement C3, C5b-9, and fibrinogen deposition. Culture of the bullous fluid was negative.