Right Ventricular Paraganglioma Mimicking Coronary Artery Aneurysm

Abstract

Background

Paragangliomas are rare neuroendocrine tumors arising from chromaffin cells, often associated with excess catecholamine production. Cardiac paragangliomas are particularly uncommon, accounting for <1% of all cardiac tumors.

Case Summary

We report a case of a right ventricular mass that was initially misidentified as a pericardial cyst on imaging but was ultimately diagnosed as a benign paraganglioma deriving from hereditary paraganglioma and pheochromocytoma syndrome after further diagnostic evaluation and treatment.

Discussion

This case highlights how rare pathologies may mimic other conditions, emphasizing the complexity and importance of a thorough diagnostic work-up in identifying cardiac paragangliomas.

Take-Home Messages

Cardiac paragangliomas are exceptionally rare tumors that can mimic more common cardiac pathologies, making diagnosis challenging. Multimodal evaluation and broad differential diagnosis are essential in evaluating cardiac masses, especially when initial findings are inconclusive or suggest alternative diagnoses.

Graphical Abstract

History of Presentation

A 49-year-old healthy woman had 3 weeks of orthostatic dizziness and ongoing exertional dyspnea over several months. The patient was previously on propranolol for migraines, but the symptoms persisted despite the discontinuation of the medication a week before visiting the cardiology clinic for low blood pressure readings.

Take-Home Messages

• •Cardiac paragangliomas are exceptionally rare tumors that can mimic more common cardiac pathologies, making diagnosis challenging.
• •Multimodal evaluation and broad differential diagnosis are essential in evaluating cardiac masses, especially when initial findings are inconclusive or suggest alternative diagnoses.

Physical examination and vitals were unremarkable at the cardiology clinic.

Past Medical History

The patient has a history of migraine and constipation-predominant irritable bowel syndrome.

Differential Diagnosis

The initial differential diagnoses included congestive heart failure, cardiac tamponade, pulmonary hypertension, pericarditis, myocarditis, valvular heart disease, cardiac arrhythmia, pulmonary embolism, COVID-19, postural orthostatic tachycardia syndrome, platypnea-orthodeoxia, and medications. These were ruled out through history, clinical assessment, and imaging studies.

Investigations

The transthoracic echocardiogram (TTE) showed an echolucent structure compressing the right atrial (RA) free wall, suspicious for a benign pericardial cyst (Figure 1, Video 1, Video 2, Video 3). Subsequent cardiac magnetic resonance imaging (MRI) was limited due to the lack of T1- and T2-weighted images, but based on the cardiac MRI, the mass appeared hypointense to isointense on balanced steady-state free precession (bSSFP) (Figure 2, Video 4) and showed heterogeneous enhancement on late gadolinium enhancement (LGE) (Figure 3). The differential diagnosis included a cardiac tumor versus a vascular structure (including a large RCA aneurysm). Due to the lack of dedicated T1- and T2-weighted images with and without fat saturation, the cardiac MRI study was suboptimal and could not further narrow down the differential diagnosis. The electrocardiogram-gated coronary computed tomography angiogram (CTA) showed an arterial phase–enhancing 4.8 × 4.1 × 2.9 cm mass located in the right AV groove, exerting a mass effect on RA and RV (Figure 4, Videos 5 and 6). Three-dimensional volume rendering of the CTA using curved multiplanar reconstruction depicted dilation of the mid to distal RCA (Figure 5, Video 7). Because of the imaging findings and persistent symptoms, the patient was referred to the emergency department for further evaluation.

Figure 3.

Cardiac Magnetic Resonance Imaging

4-chamber LGE image shows the right AV groove mass (asterisk) with heterogeneous enhancement. AV = atrioventricular LGE = late gadolinium enhancement.

Figure 1.

Transthoracic Echocardiogram

TTE shows an echolucent structure (yellow circle) in parasternal long axis view (A), substernal view (B), and parasternal short axis view (C). TTE = transthoracic echocardiogram.

Figure 2.

Cardiac Magnetic Resonance Imaging

bSSFP cine still image shows a mobile mass in the right AV groove that is hypointense to isointense. AV = atrioventricular; bSSFP = balanced steady-state free precession.

Figure 4.

Coronary Computed Tomography Angiogram

Coronary CTA transverse view (A) and coronal view (B) show an enhancing structure (yellow circle) inseparable from the RCA (red arrow). CTA = computed tomography angiogram; RCA = right coronary artery.

Figure 5.

Coronary Computed Tomography Angiogram

Three-dimensional volume rendering of the CTA using curved multiplanar reconstruction depicts dilation of the mid to distal RCA. CTA = computed tomography angiogram; RCA = right coronary artery.

After admission, the patient underwent coronary angiography, which revealed a massive circular structure emanating from the mid to distal RCA that filled late with contrast (Figure 6, Video 8).

Management (Medical/Interventions)

Cardiothoracic surgery was consulted for urgent operative intervention. The intraoperative transesophageal echocardiogram (TEE) showed an extrinsic mass adherent to the mid-RCA compressing 50% of the RA (Figure 7, Video 9, Video 10, Video 11). Further surgical exploration revealed a cardiac tumor arising from the RV. The mass was excised in its entirety for pathology evaluation, while a saphenous vein interposition graft was created in the excised portion of the RCA. After resection, the patient’s symptoms improved, and she was discharged 5 days later with a regimen of aspirin 81 mg daily, metoprolol tartrate 12.5 mg twice daily, and atorvastatin 20 mg nightly. The pathology report with positive markers including synaptophysin, chromogranin A, CD56, and S100 was diagnostic for benign paragangliomas.

Figure 7.

Transesophageal Echocardiogram

Intraoperative TEE ME 4-chamber (A), ME RV inflow-outflow (B), and ME LA (C) views clearly delineate an extrinsic mass compressing the RA (yellow circles). LA = left atrium; ME = mid-esophageal; RA = right atrium; RV = right ventricle; TEE = transesophageal echocardiogram.

Figure 6.

Coronary Angiogram

Coronary angiogram shows a circular structure (yellow circle) emanating from the mid to distal RCA. RCA = right coronary artery.

Postoperatively, the patient was referred to endocrinology where urinary metanephrines were collected, and she was screened for succinate dehydrogenase (SDH) complex subunit genes (SDHA, SDHB, SDHC, and SDHD). Results showed a 24-hour urine metanephrine level of 50 mcg/24 h, a 24-hour urine normetanephrine level of 157 mcg/24 h, a plasma norepinephrine level of 397 pg/mL, a plasma epinephrine level of 29 pg/mL, and a plasma dopamine level of 35 pg/mL. Genetic screening revealed the patient as an SDHC gene mutation (deletion of exon 4) carrier, consistent with hereditary paraganglioma and pheochromocytoma syndrome. The patient was referred to genetic counseling.

Postoperative computed tomography (CT) of the abdomen and pelvis showed no evidence of a metastatic or recurrent paraganglioma, and an E-consult was placed at Mayo Endocrinology for opinions on whether the patient might benefit from Ga-68 DOTATATE to screen for metastasis, given that the excision surgery was performed before any hormonal work-up. Because of the lower sensitivity of nuclear medicine scans in capturing smaller tumors, especially in the heart and bladder,¹ Mayo Endocrinology recommended magnetic resonance imaging (MRI) of the heart and abdomen/pelvis as a part of routine surveillance.

Discussion

Paragangliomas are neuroendocrine tumors that are indistinguishable from pheochromocytomas at the cellular level.² They are classified into two categories: sympathetic and parasympathetic. Sympathetic paragangliomas usually secrete catecholamines and are classically found to be distributed along the sympathetic chain, while parasympathetic paragangliomas are usually nonfunctional and typically found along glossopharyngeal and vagal nerves in the neck and base of the skull.^2,3 Up to 50% of paragangliomas are found to be metastatic, with 37% 5-year mortality.⁴

Standard work-up for cardiac paragangliomas involves assessment of neuroendocrine activity (screening for elevated metanephrines), tumor assessment with dedicated cardiac CT, MRI, TTE, and using somatostatin receptor–based radiopharmaceuticals with positron emission tomography (either Ga-68 DOTATATE or Ga-68 DOTATOC based on pathogenic and receptor expression variation) to evaluate for metastasis.⁵ Genetic screening for SDHx, multiple endocrine neoplasia type 2, neurofibromatosis type 1, and Von Hippel-Lindau disease is also increasingly recommended as a part of work-up.⁶ Negative family history cannot be used to exclude the diagnosis because the germline mutations are implicated in up to 40% of cardiac paragangliomas.^2,5, 6, 7, 8 Surgical excision remains the gold standard for treatment, although transplant may be necessary in cases of severe cardiac infiltration.⁵

Our unique case presented disguised as an RCA aneurysm or a pericardial cyst on multiple imaging modalities due to the lack of functionality, anatomic location, and the inherent vascularity of cardiac paragangliomas. As such, the main work-up involved standard imaging including echocardiogram, coronary CTA, and cardiac magnetic resonance, followed immediately by surgical excision. In retrospect, T1 and T2 weighted cardiac MRI images may have helped better distinguish between the various differentials for the mass, but the sequences were unfortunately not obtained. After the pathology came back as a benign paraganglioma, the patient was referred to endocrinology for the additional work-ups specific to the tumor, including urine metanephrines, genetic screening, and CT of the neck, chest, abdomen, and pelvis. The disguised presentation led to reversal of standard work-up and treatment.

Follow-Up

A week after discharge, the patient underwent a follow-up TTE that was unremarkable except for a small pericardial effusion. Her evaluation by cardiology and cardiac surgery were also unremarkable. CT of the chest, abdomen, and pelvis was unremarkable 1 year postresection, and the patient was referred for MRI of the heart and abdomen/pelvis.

Conclusions

This case highlights the complex diagnostic process of radiolucent cardiac densities and the inherent challenges that accompany atypical presentations of well-known pathologies. Disease processes that have differing managements can mimic each other despite thorough multimodal investigations, such as the paraganglioma that mimicked an RCA aneurysm in our case. It emphasizes the importance of leading investigations with a thorough differential to ensure complete work-up and treatment.

Visual Summary.

Timeline of the Case

Timeline	Events
Day 1	A 49-year-old woman presented to the cardiology clinic with 3 wk of orthostatic dizziness and ongoing exertional dyspnea over several months.
Day 41	The transthoracic echocardiogram (TTE) showed an echolucent structure adjacent to and compressing the right atrial free wall suspicious for a pericardial cyst. Cardiac magnetic resonance was recommended, but because of difficulties in communication, the patient underwent cardiac magnetic resonance 4 mo after the TTE.
Day 157	Cardiac magnetic resonance showed a right atrioventricular groove mass. The patient was referred to the emergency department, where the computed tomography angiogram of coronary arteries showed a very large right coronary artery (RCA) aneurysm. The patient was admitted for further work-up.
Day 160	The coronary angiogram revealed a massive circular structure in the mid/distal RCA region that fills late with contrast.
Day 161	The patient was taken to the operating room, and the mass was excised by cardiothoracic surgery, with a saphenous vein interposition graft for the excised portion of the RCA.
Day 166	The patient was discharged with follow-up appointments for oncology and endocrinology. Surgical pathology revealed the mass to be a paraganglioma.
Day 367	Endocrinology work-up showed positive results for SDHC gene mutation (deletion of exon 4) consistent with hereditary paraganglioma and pheochromocytoma syndrome.

Funding Support and Author Disclosures

The authors have reported that they have no relationships relevant to the contents of this paper to disclose.

Appendix

Video 1

Transthoracic Echocardiogram

TTE shows an echolucent structure in parasternal long axis view. TTE = transthoracic echocardiogram.

Video 2

Transthoracic Echocardiogram

TTE shows an echolucent structure in parasternal short axis view. TTE = transthoracic echocardiogram.

Video 3

Transthoracic Echocardiogram

TTE subcostal view shows an ovoid mass compressing the RA. RA = right atrium; TTE = transthoracic echocardiogram.

Video 4

Cardiac Magnetic Resonance Imaging

bSSFP cine shows a mobile mass in the right atrioventricular groove that is hypointense to isointense.

Video 5

Coronary Computed Tomography Angiogram

Coronary CTA transverse view shows an enhancing structure inseparable from the RCA. CTA = computed tomography angiogram; RCA = right coronary artery.

Video 6

Coronary Computed Tomography Angiogram

Coronary CTA coronal view shows an enhancing structure inseparable from the RCA. CTA = computed tomography angiogram; RCA = right coronary artery.

Video 7

Coronary Computed Tomography Angiogram

Three-dimensional volume rendering of the CTA using curved multiplanar reconstruction depicts dilation of the mid to distal RCA. CTA = computed tomography angiogram; RCA = right coronary artery.

Video 8

Coronary Angiogram

Coronary angiogram shows a circular structure emanating from the mid to distal RCA. RCA = right coronary artery.

Video 9

Transesophageal Echocardiogram

Intraoperative TEE ME 4-chamber view clearly delineates an extrinsic mass compressing the RA. ME = mid-esophageal; RA = right atrium; TEE = transesophageal echocardiogram.

Video 10

Transesophageal Echocardiogram

Intraoperative TEE ME RV inflow-outflow view clearly delineates an extrinsic mass compressing the RA. ME = mid-esophageal; RA = right atrium; RV = right ventricle; TEE = transesophageal echocardiogram.

Video 11

Transesophageal Echocardiogram

Intraoperative TEE ME LA view clearly delineates an extrinsic mass compressing the RA. LA = left atrium; ME = mid-esophageal; RA = right atrium; TEE = transesophageal echocardiogram.