IgG4-related disease with possible myocardial involvement.

IgG4-related disease is characterized by mass lesions, a dense lymphoplasmacytic infiltrate with immunohistochemical positivity for IgG4, storiform fibrosis and, frequently, elevated serum IgG4 levels. It can be multisystemic; however, myocardial involvement, which is objectively determined by imaging tests, has not been described in the medical literature. We report the case of a man with IgG4-related disease with possible myocardial involvement, detected by cardiac magnetic resonance. This raises the question of a differential diagnosis with other diseases such as sarcoidosis and Fabry disease, the differential diagnosis of which is of great importance due to its therapeutic impact.