Primary extramedullary plasmacytoma in the atria of the heart.

A rare case of primary extramedullary plasmacytoma of the heart is described. The large space-occupying tumor in the atrial wall and its associated significant pericardial effusion caused marked impairment of cardiovascular function. The diagnosis was made via intravenous biopsy. Immunohistochemistry demonstrated CD45 and kappa light chain expression. Other B-cell- and T-cell-specific lymphoid markers were negative. Elevated kappa light chain was detected in serum by immunofixation electrophoresis. The differential diagnosis of plasmacytoma should be considered in cardiac tumors when routine screening is negative with lymphoid (CD20, CD3) and soft tissue immunohistochemical markers.