AIMS: The cutaneous manifestation of IgG(4)-related disease has rarely been reported. The aim of this study is to identify and describe the cutaneous manifestations associated with IgG(4)-positive plasma cell infiltration in the skin. METHODS: The authors investigated two cases of IgG(4)-related disease with solitary skin lesions and compared the immunohistochemical characteristics of infiltrating cells among IgG(4)-related disease, Kimura's disease and cutaneous pseudolymphoma. RESULTS: IgG(4)-related disease manifested as an indurated plaque on the anterior chest in one case and a nodule on the toe in the other case. Histopathologically, skin lesions of IgG(4)-related disease showed a dense, mixed-cell infiltrate containing lymphocytes, plasma cells and eosinophils along with fibrosis. Plasma cells stained positively with anti-IgG and anti-IgG(4) antibodies, and the ratio of IgG(4)+/IgG+ cells was more than 50%. Serum levels of IgG and IgG(4) were not elevated and no lesions were found in other organs. Skin samples taken from Kimura's disease showed histopathological features similar to those of IgG(4)-related disease. The proportion of IgG(4)+/IgG+ was high in Kimura's disease, but not in cutaneous pseudolymphoma. CONCLUSIONS: The solitary skin lesions of IgG(4)-related disease were similar histologically and immunohistochemically to the skin lesions of Kimura's disease. The concept of IgG(4)-related disease may help clarify the pathomechanism of diseases of unknown aetiology that possess features of IgG(4)-related disease.
AIMS: The cutaneous manifestation of IgG(4)-related disease has rarely been reported. The aim of this study is to identify and describe the cutaneous manifestations associated with IgG(4)-positive plasma cell infiltration in the skin. METHODS: The authors investigated two cases of IgG(4)-related disease with solitary skin lesions and compared the immunohistochemical characteristics of infiltrating cells among IgG(4)-related disease, Kimura's disease and cutaneous pseudolymphoma. RESULTS: IgG(4)-related disease manifested as an indurated plaque on the anterior chest in one case and a nodule on the toe in the other case. Histopathologically, skin lesions of IgG(4)-related disease showed a dense, mixed-cell infiltrate containing lymphocytes, plasma cells and eosinophils along with fibrosis. Plasma cells stained positively with anti-IgG and anti-IgG(4) antibodies, and the ratio of IgG(4)+/IgG+ cells was more than 50%. Serum levels of IgG and IgG(4) were not elevated and no lesions were found in other organs. Skin samples taken from Kimura's disease showed histopathological features similar to those of IgG(4)-related disease. The proportion of IgG(4)+/IgG+ was high in Kimura's disease, but not in cutaneous pseudolymphoma. CONCLUSIONS: The solitary skin lesions of IgG(4)-related disease were similar histologically and immunohistochemically to the skin lesions of Kimura's disease. The concept of IgG(4)-related disease may help clarify the pathomechanism of diseases of unknown aetiology that possess features of IgG(4)-related disease.