Linear deposits of IgM along the dermo-epidermal junction possibly associated with non-classical clinical features in bullous pemphigoid

The current diagnostic standard for bullous pemphigoid (BP) provides the linear deposition of IgG autoantibodies and/or C3 fraction of the complement against structural proteins of the dermo-epidermal junction (DEJ) at direct immunofluorescence (DIF) microscopy. Instead, the significance of linear IgM junctional staining in cutaneous immunopathology is not clear denoting many known dermatological disorders. Herein is reported a case of BP characterized by the finding of IgM linear deposits at the DEJ along with non-classical clinical features.