A novel case report of isolated cardiac myxedematosus.

We report a first known case of isolated cardiac myxedematosus associated with a severe systolic and diastolic cardiomyopathy. Our patient did not have any clinical evidence of systemic scleromyxedema or paraproteinemia, both of which have been reported in association with cardiac mucin deposits. Mucinosus has been described in patients with systemic lupus erythematous; however, cardiac deposits have not been reported. While IVIg has been used as a treatment in previously reported cases of cardiac scleromyxedema, its clinical benefit remains unclear in isolated cardiac myxedematosus.