[A case of latent cardiac sarcoidosis in reference to differential diagnosis from giant cell myocarditis].

We report a case of latent cardiac sarcoidosis in reference to differential diagnosis from giant cell myocarditis. A 68-year-old woman succumbed to subarachnoid hemorrhage and acute myocardial infarction within a period of 3 days. Autopsy revealed white fibrotic lesions in the lateral wall of the left ventricle and interventricular septum of the heart in addition to acute myocardial infarction of the anterior wall. Histology showed fibrotic granulomatous lesions with infiltration of lymphocytes and epithelioid cells. Many multinucleated giant cells of Langhans and foreign body types were scattered among these lesions. There was no lesion in the bilateral hilar lymph nodes, but typical epithelioid granuloma was noticed in the lymph node of the carina, liver, and spleen. So we concluded that the heart lesion was a case of cardiac sarcoidosis. Striation could not be seen in the multinucleated giant cells of the cardiac sarcoid lesion, and, using light microscopy, it seemed to us that these cells had no relation to the cardiac muscles. However, by immunohistochemistry (PAP method) some giant cells tested positive for myoglobin, and others tested positive for lysozyme. The fact that giant cells are not always derived from the cardiac muscle can't be used, as a criterion for the diagnosis of cardiac sarcoidosis. Giant cells in the lung and lymph nodes tested positive only for lysozyme. Hence, using only cardiac histology, it is difficult to make a differential diagnosis between cardiac sarcoidosis and giant cell myocarditis, especially in cases where there is multiple organ involvement.