A case of IgG4-related disease diagnosed by a skin biopsy

A 64-year-old man presented with a 3-year history of non-pruritic multiple brown papules on his face and trunk. Histopathological examination of a skin biopsy revealed a moderate dermal infiltration of lymphocytes and plasma cells around the vessels and adnexal structures with hyalinization. Immunostaining showed that a large proportion (>40%) of the infiltrating plasma cells were IgG4-positive. Laboratory investigations revealed raised levels of serum IgG and IgG4. A CT scan revealed a ground-glass pattern and lymphadenopathy in the lung, together with parotid swelling. Based on the clinical and histological findings, the skin disease was diagnosed as a cutaneous presentation of IgG4-related disease. After the systemic administration of 30 mg/day of prednisolone, a rapid response was obtained and the pulmonary symptoms and skin lesion were improved. However, tapering of prednisolone to 8 mg/day resulted in recurrence. IgG4-related disease is a newly recognized condition that affects multiple organs. Cutaneous features could be the first presentation of IgG4-related disease. Therefore, it is important for dermatologists to be aware of this disease.