sarcoidosis is an idiopathic granulomatous disease characterized by the presence of non - caseating granulomas in affected tissues . the lungs are most often involved , but it may affect any organ , particularly the heart , skin , eyes , reticuloendothelial system , kidneys , and central venous system ( 1 , 2 ) . postmortem studies indicate that cardiac involvement ranges from 20% to 25% , with higher prevalence in japan and scandinavia ( 2 , 3 ) . clinically , the cardiac involvement is most often silent and becomes apparent in only about 5% of patients . symptoms of cardiac sarcoidosis are nonspecific and depend on the location and extent of the granulomatous inflammation . this may include conduction abnormalities with bundle branch block or atrioventricular block ( 25 - 30% ) , ventricular arrhythmias ( 23% , ranging from isolated premature ventricular beats to sustained or non - sustained ventricular tachycardia [ vt ] ) , and even ventricular fibrillation that leads to sudden death ( 35% ) ( 3 ) . cardiac sarcoidosis may also cause systolic or diastolic heart failure with poor prognosis ( 1 ) . non - caseating granulomatous infiltration and fibrosis are likely to be located in the left ventricle ( lv ) , but right ventricle ( rv ) free wall involvement may also be present in up to 40% of the cases . rv involvement may mimic arrhythmogenic right ventricular dysplasia ( arvd ) on an electrocardiographic ( ecg ) and image findings . arvd is a rare genetic condition characterized by fibro - fatty tissue infiltration , ventricular dysfunction , and arrhythmias , typically of the rv . differentiation between sarcoidosis and arvd can be especially challenging with biventricular involvement while differentiation is important with regard to therapeutic options and prognosis . in this paper , we presented a patient who was diagnosed as having arvd on the basis of clinical symptoms and ecg and image findings while postmortem examination showed cardiac sarcoidosis . our institutional review board declared that formal ethical approval for a retrospective analysis of clinically obtained data in this report was not needed . a 53-year - old woman was referred to our institution after a ventricular fibrillation and a successful resuscitation . thoracic ct , performed to rule out pulmonary embolism , showed a rv enlargement without obvious cause ( fig . a few slightly enlarged mediastinal lymph nodes were observed but were not suspected ( fig . a cardiac mri showed a dilated rv with global hypokinesia and an end - diastolic volume of 130 ml / m ( normal value : 67  10 ml / m ; 95% confidence interval [ ci ] , 48 - 87 ml / m ) ( 5 ) , with an ejection fraction of 24.5% ( normal value : 63  8% ; 95% ci , 47 - 80% ) ( 5 ) . the lv morphology and function were normal ( ejection fraction , 63% ) , and pericardial effusion was not observed . extended late gadolinium enhancement ( lge ) was present in large parts of the rv free wall , rv outflow tract , and moderator band , while limited patchy lge was present in the apical interventricular septum and basal inferolateral lv wall ( fig . both mediastinum and lungs were unremarkable except for a minimal right - sided pleural effusion . arvd was suspected according to the mri findings and the revised arvd task force criteria ( 6 ) . five months later , the patient was readmitted with an electrical storm unresponsive to drug therapy . an endocardial catheter ablation was not successful , most likely due to a subepicardial substrate for induced vt . a cardiac ct , performed prior to epicardial mapping , showed normal coronary arteries and no pulmonary or mediastinal abnormalities . an endomyocardial biopsy of the rv was performed , but the histologic findings were inconclusive . l ; reference value , 240 - 560 g / l ) . however , imaging features met the criteria for arvd ( 6 ) . an epicardial mapping confirmed a subepicardial substrate , which was targeted by a catheter ablation . the patient developed purulent pericarditis caused by an enterotoxic s. aureus two days after the epicardial ablation therapy and died of toxic shock syndrome within 24 hours . the post - mortem examination demonstrated massive sarcoidosis involving the heart , both lungs , and the thyroid gland . these areas included the rv , extensively , and focal areas in the lv and the interventricular septum , with the same distribution of lge on the mri ( fig . microscopic examination revealed a non - caseating granulomatous inflammation , containing epithelioid histiocytes , multinucleated giant cells , and fibrosis . in the literature , there is an increasing number of case reports and series reporting sarcoidosis with predominant rv involvement . this usually presents with arrhythmia and morphological or functional rv abnormalities , generally in association with other clinical or radiological findings that pointed to a sarcoidosis diagnosis , such as enlarged mediastinal lymph nodes or pulmonary involvement ( 8 , 9 , 10 ) . three of the 20 patients ( 15% ) were found to have non - caseating granulomas on biopsy , consistent with cardiac sarcoidosis . it is noteworthy that patients with histopathologic diagnosis of arvd were no different from patients with sarcoidosis granulomas , regarding most clinical variables , such as age , symptoms , ecg abnormalities , late potentials , arrhythmias , or findings on a chest radiography or mri . the study demonstrated that cardiac sarcoidosis may account for an arvd phenotype in an unexpectedly high proportion of cases . the only variable that was found significantly associated with cardiac sarcoidosis was lv dysfunction with an ejection fraction below 50% ( 3 of 3 sarcoidosis patients versus 2 of 17 arvd patients ) . the authors suggested that lv function could be useful in the differential diagnosis , as lv dysfunction is more likely present in cardiac sarcoidosis than in arvd ( 9 ) . in our patient , normal lv function and , especially , the absence of extracardiac manifestations of sarcoidosis , both clinically and radiologically , suggested the diagnosis of arvd with biventricular involvement . arvd and sarcoidosis with biventricular involvement may have similar lge patterns . in both cases , patchy enhancement is usually transmural in the rv and subepicardial and/or midwall in the lv . in arvd , lge can be present in up to a third of patients ( 11 , 12 ) and is usually located in the rv free wall , in the outflow tract , and in the posterior / inferior wall . enhancement is associated with scar tissue ( 12 ) . in sarcoidosis , cardiac lge is present in up to a fourth of patients ( 13 ) . lge distribution is usually subepicardial and/or midwall , and commonly involved locations are the rv side of the interventricular septum and the lv basal anterolateral and anteroseptal regions ( 14 ) . transmural lesions are associated with poor lv ejection fraction ( 15 ) . in the literature , we found only one case of clinically isolated cardiac sarcoidosis similar to our patient ( 10 ) . to the best of our knowledge , there are no other cases that demonstrate the exact correlation between mri and pathology examinations of cardiac sarcoidosis . it is important to be aware that sarcoidosis can mimic arvd and to take into consideration the differential diagnosis cardiac sarcoidosis , even when the revised arvd task force criteria are fulfilled .
a 53-year - old woman was referred for ventricular fibrillation with resuscitation . 
 a ct - angiography showed signs of a right ventricular enlargement without obvious cause . 
 a cardiac mri demonstrated a dilated and hypokinetic right ventricle with extensive late gadolinium enhancement . 
 arrhythmogenic right ventricular dysplasia ( arvd ) was suspected according to the " revised arvd task force criteria " . 
 an endomyocardial biopsy was inconclusive . 
 the patient developed purulent pericarditis after epicardial ablation therapy and died of toxic shock syndrome . 
 the post - mortem pathologic examination demonstrated sarcoidosis involving the heart , lungs , and thyroid gland .