A chronic autoimmune subepidermal bullous disease characterized by grouped pruritic lesions such as papules, urticarial plaques, erythema, and herpetiform vesiculae, with a predominantly symmetrical distribution on extensor surfaces of the elbows (90%), knees (30%), shoulders, buttocks, sacral region, and face of children and adults. Erosions, excoriations and hyperpigmentation usually follow. It may also appear as a consequence of gluten intolerance.

A granulomatous inflammation leading to multiple granuloma formation, which is a specific type of inflammation. A granuloma is a focal compact collection of inflammatory cells, mononuclear cells predominating, usually as a result of the persistence of a non-degradable product and of active cell mediated hypersensitivity.