IgG4-related skin manifestations in patients with IgG4-related disease

We describe two cases of IgG4-related disease associated with skin manifestations with IgG4-positive plasma cells. The first patient was a 52-year-old woman with a 3-year history of IgG4-related sialadenitis who presented with pruritic, indurated erythematous lesions on the auricle, postauricular and submandibular regions and neck. A skin biopsy showed infiltration of IgG4-positive plasma cells in the subcutaneous tissue. The second patient was a 53-year-old woman with IgG4-related lesions in the ocular adnexal tissues and nasal cavity who presented with pruritic, indurated erythema on the cheek and submandibular region. Histopathological examination of a skin biopsy revealed a dense, patchy infiltrate comprised of lymphocytes, IgG4-positive plasma cells and eosinophils around blood vessels and sweat glands in the entire dermis and subcutis. The skin lesions in these cases were considered to be skin manifestations of IgG4-related disease. The findings of these two cases together with the three reported cases of IgG4-related disease with skin manifestations in the literature suggest that IgG4-related skin lesions may appear on the scalp, face, neck, auricle and postauricular regions during the course of IgG4-related disease.