A case of alopecia as IgG4-related skin disease.

A 53-year-old man with autoimmune pancreatitis as IgG4-related disease presented alopecia. Immunostaining showed perifollicular infiltration of IgG4-positive cells and perifollicular/intrafollicular infiltration of predominantly CD4-positive cells, especially in the upper and lower parts. Alopecia areata is characterized by perifollicular/intrafollicular lymphocyte infiltration of the lower bulb and inflammation in the upper dermis. We determined the patient had IgG4-related skin disease, rather than alopecia areata. Alopecia as IgG4-related skin disease has not been reported previously.