Cardiac Amyloidosis - IV

Gross pathology of valvular and septal involvement in amyloidosis.   A.  Left atrium and mitral valve show distinct plaques of yellow-ochre plaques that bulge on the endocardial surface of these two structures.   Some thebesian veins opening into the atrium are distinctly visible in left side of the image.    B.  Anterior leaflet of the tricuspid valve showing coarse plaques protruding above its atrial surface.  They resemble organizing vegetation material, but on microscopic examination they are composed of amyloid deposits and not of organizing fibrin deposits or fibrous tissue.  Note the coarse, nodular, fibrin thrombi lodged in the trabecular portion of the atrial pectinate muscles.   C. Long axis view of the left atrium, mitral valve and aortic valve.   The amyloid plaques and small nodules are easily identified over the endocardium of the atrium and the left ventricular outflow tract.   Coarser deposits are present on the anterior and posterior leaflets of the mitral valve as well as the posterior and right leaflets of the aortic valve.  The fibrous portion of the interventricular septum just below the aortic valve shows only scant yellow-ochre plaques.  D.  This four chamber view of a heart weighing more than 1000 grams shows distinct asymmetric septal hypertrophy.  Note the faint discoloration of the subendocardial myocardium in both the interventricular septum and the left ventricular free wall.   In addition there is fine granularity of the atrial endocardium.
Microscopic examination of amyloid deposits requires demonstration that the deposits are in fact amyloid and in many instances identification of the protein being deposited.