Immunoelectron microscopy in subepidermal autoimmune bullous diseases: a prospective study of IgG and C3 bound in vivo in 32 patients.

Thirty-two patients suffering from subepidermal autoimmune bullous disease were studied prospectively by clinical examination and immunoelectron microscopy. Clinically, 1 patient had herpes gestationnis, 14 typical bullous pemphigoid (BP), 3 epidermolysis acquisita (EBA), 3 cicatricial pemphigoid (CP), and 11 patients overlapping clinical diseases. These 11 patients shared clinical features of BP, EBA, or CP and a clinical diagnosis could not be done safely. Immunoelectron microscopy revealed diaminobenzidine deposits in 20 patients on the epidermal side of dermo-epidermal junction in the lamina lucida as in BP. In 5 patients, deposits located mostly under the anchoring fibril zone, in the floor of a sublamina densa dermoepidermal separation for 2 of them, were consistent with a diagnosis of EBA. In 6 patients, deposits were located mostly in the lamina densa, in the floor of a dermoepidermal separation occurring in the lamina lucida for 3 of them. This suggests that some of these 6 patients had neither EBA or BP, but another autoimmune bullous disease again, an uncharacterized component of dermoepidermal junction located in the lamina densa. Finally, a correlation exists between the sites of IgG and/or C3 components on epidermal or dermal side of dermoepidermal junction and the presence or absence of characteristic clinical features such as scar, milia formation, or mucosal involvement.