Cardiac Amyloidosis - VII

Perimyocytic and arteriolar amyloid deposits.   A.  Amyloid deposits are present in perimyocytic location surrounding individual myocytes and also involving the endocardium (H&E X50).  B. Other stains that highlight the interstitial connective tissue can also show the presence of amyloid.  In this micrograph the myocardium is stained with Masson’s trichrome.  The amyloid deposits appear as dull, pale, blue-gray material surrounding individual myocytes.  In contrast the fibrous tissue shows the typical brighter crisp blue of fibrous tissue mixed in with the amyloid deposits. (Masson’s trichrome, X100). Ultrastructural examination can readily differentiate collagen fibrils from amyloid fibrils.   C. The Thioflavin-S highlights perimyocytic deposits of amyloid as bright-lighter blue compared to the darker blue of the myocytes under ultraviolet light microscopy. (Thioflavin-S, X100).  D.  Amyloid deposits follow the contours of the myocytes without forming nodules or producing atrophy of the myocytes.  (H&E X100).  E. Immunohistochemistry of the case shown in D is positive for kappa-light chains, showing the exact same pattern of perimyocytic deposition.  In addition, two small arteries are present and also show amyloid deposition.   (Immunohistochemical stain for kappa-light chains.  X100).  F.  Interstitial and arteriolar deposits of amyloid in an endomyocardial biopsy (H&E, X400).  G.  The same case shows bright amyloid deposits in arteriolar as well as interstitial location in this Thioflavin-S stain examined under ultraviolet light microscopy (Thioflavin-S, X400). The atrial and ventricular myocardium may also show a nodular pattern of infiltration by amyloid.