The Clinical and Histological Intersection of Cardiac Sarcoidosis and Giant Cell Myocarditis

Abstract

The clinical and imaging features of cardiac sarcoidosis (CS) and giant cell myocarditis (GCM) are occasionally indistinguishable. This is a case of heart block and ventricular tachycardia where cardiac MRI, fluorodeoxyglucose positron emission tomography (FDG-PET) and biopsy revealed intermediate clinicohistologic phenotype between CS and GCM. This highlights gaps in the management of overlap conditions.

Keywords: biopsy; cardiac sarcoidosis; giant cell myocarditis; histology; management; overlap; pet scans.

Figure 1. EKG showing sinus rhythm, right bundle branch block and left anterior fascicular block

Figure 2. Cardiac MRI (CMR) showing well-demarcated sub-epicardial increased T2 signal suggesting edema in the anteroseptal wall and inferoseptal wall extending from base to apex

Figure 3. Cardiac PET scan with high right ventricular and septal intake

PET: positron emission tomography.

Figure 4. Biopsy photomicrographs showing features of both sarcoidosis and giant cell carditis

(A) Medium power view (20x) of H&E-stained section shows a focus of mixed inflammatory cells in the myocardium. (B) Trichrome stain (40x) highlights the early fibrosis associated with the focus of inflammation with a rare giant cell (arrow). (C) High power (40x) of H&E-stained section shows a focus of predominantly eosinophils. (D) Congo red-stained section (40x) is negative for amyloid but shows a giant cell (arrow) without granuloma formation. H&E: hematoxylin and eosin.