Cardiac Amyloidosis - IX

Right ventricular endomyocardial biopsy showing involvement of venules, adipose tissue and myocardial interstitium.  A. Tortuous eosinophilic “amorphous” material aggregates are visible towards the left side of the micrograph, as well as interspersed with the adipose tissue (H&E X50).   B. Immunohistochemical staining for transthyretin shows that the tortuous material is amyloid present in small collapsed veins and arterioles.  It also shows amyloid in the adipose tissue and in the myocardial interstitial space. (TTR immunohistochemistry, X50)

While the specific nature of the amyloid deposits in the heart (i.e. kappa or lambda light chains or transthyretin deposition) is important for diagnosis and management, the first step in many centers is to perform a Congo red stain to detect amyloid.