A Case of the Linear Dermatitis-like Subepidermal Blistering Disease Diagnosed as Granular C3 Dermatosis

Abstract

A 71-year-old man presented with itchy linear eruptions that had developed repeatedly on both sides of his lumber area and around the knees for about three years. Although they were treated with topical corticosteroids under the diagnosis of eczema, bullous lesions arose to accompany the erosions for approximately half a year. The clinical picture resembled the linear dermatitis. Histopathologically, a subepidermal bulla with an infiltration of eosinophils and lymphocytes was observed. Serum anti-BP180NC16a antibodies were negative. By direct immunofluorescence, granular and linear deposition of C3 on the basement membrane was noted, but IgG and IgA deposition was negative. IgG and IgA reactivity on indirect immunofluorescence using nomal human skin was also negative. By indirect immunofluorescence using 1M sodium chloride-split skin, weak reactivity for serum IgA on the epidermal side of the basement membrane was observed, whereas intra-bullous exudate showed no reactivety for either IgG or IgA. All immunoblottings and enzyme-linked immunosorbent assays examined also gave negative results. From these results, our patient was diagnosed with granular C3 dermatosis. To elucidate the etiology of granular C3 dermatosis, careful investigation of more cases in the future is required.