Cardiac paraprotein associated with Waldenstrom's macroglobulinemia: a case report

A case of myocardial paraprotein deposition in a patient with Waldenstrom's macroglobulinemia is presented. Routine light microscopy revealed diffuse widening of interstitial regions by pale eosinophilic material that had a grayish cast on trichrome stains and was Congo red negative. Immunofluorescence showed strong immunoglobulin M and kappa light chain staining around blood vessels but predominantly around myocytes. Ultrastructural examination revealed massive deposition of flocculent electron-dense material around myocytes and occasionally around blood vessels.