Background:

Cardiac Sarcoidosis (CS) is often labelled “the great masquerader” due to varied clinical presentations and an overlap with other cardiac diseases. A definite diagnosis can be difficult to make and often requires a multimodal approach. Here we present the case of a patient with clinical findings typical for arrhythmogenic cardiomyopathy (ACM) but with the ultimate diagnosis of CS.

Clinical Case:

A 53-year-old male patient was referred to our clinic due to new onset of heart failure (HF)with dyspnea, leg swelling and ascites. ECG showed sinus rhythm with a right bundle branch block. Echocardiography revealed severe right-ventricular (RV) dilation, reduced systolic RV function(Fig. 1A) and mildly reduced left ventricular (LV) ejection fraction. Coronary angiography showed an absence of coronary artery disease. Magnetic resonance imaging saw a patchy pattern of late gadolinium enhancement, predominantly in the RV (Fig.1C and 1D). Endomyocardial biopsy (EMB) from the RV revealed findings congruent with ACM , such as cardiomyocytes with enlarged nuclei, multiple depots of adipocytes (Fig. 2A) as well as fibrosis (Fig.2B). The patient had recurrent slow ventricular tachycardias (VT) with a heart rate of 130 bpm, inferior axis, and R/S transition in V3, highly suggestive for the exit site in the RV (Fig. 1B). The 2010 revised international Task Force (ITF) Criteria for ACM were fulfilled, hence diagnosis of ACM was made. Due to recurrent VT episodes despite antiarrhythmic therapy, patient was scheduled for a catheter ablation(CA). Endo- und epicardial substrate mapping in the RV showed an extended low voltage area (LVA) in the inflow tract, apex as well as in the outflow tract (Fig. 3A and 3B). Endo- and epicardial CA of VT was performed, including ablation pf fractionated and late potentials in the RV. The extensive LVA , typical for ACM localizations in the RV, strengthened our ACM diagnosis additionally. 

Abdominal ultrasound, performed for ascites work-up, showed multiple nodules of unclear aetiology in the spleen. Computed tomography (CT) revealed pulmonary lymph node enlargement. Transbronchial lung biopsy showed inflammatory infiltrates of the subepithelial region, amongst which granulomas with multinucleated giant cells were revealed (Fig. 2C). These were highlighted by CD68-IHC (Fig. 2E), leading to the diagnosis of non-necrotizing epithelioid granulomas congruent with sarcoidosis. The definite extracardiac sarcoidosis raised our suspicion of CS as an alternative aetiology of RV failure in our patient. A positron emission tomography (PET) CT scan was obtained, which showed marked active inflammation of the RV and LV (Fig.4A) as well as cervical, axillar, and mediastinal lymphadenopathy, lymph nodes along the course of iliacal and femoral vessels, hepatic and splenic involvement (Fig.4B). Hence, CS was unmasked, and treatment with prednisolone was initiated.

Conclusion: This case highlights how CS involving RV can mimic ACM. Because of the patchy nature of CS, the role of EMB in diagnosing CS is limited. Furthermore, CS can have EMB findings similar to ACM, like the presence of fatty infiltration and confluent fibrosis, which both are reported to be indirect pathological indicators for CS, as was seen in this case. Early diagnosis is essential since CS is a potentially treatable disorder as opposed to untreatable ACM. Implementing cardiac imaging like PET-CT impacts diagnosis and management of CS significantly.