Discussion

Pericardial cysts are uncommon congenital cardiac anomalies that arise from developmental abnormalities during embryogenesis. Such cysts are thought to originate embryologically from disconnected mesenchymal lacunae, which normally unite to form the pericardial coelom. The majority of cases (50–75%) are asymptomatic and are discovered incidentally during routine radiological investigations performed for other clinical indications. ^{Reference Qamar, Gulzar, Qamar, Sabry and Minhas1} Most pericardial cysts are located at the right (70%) or left (22%) cardiophrenic angle, with the remainder found in the anterior or posterior mediastinum. ^{Reference Kar and Ganguly2}

Epicardial cysts are much rarer than pericardial cysts, and their surgical management has seldom been reported. ^{Reference Gupta, Shah, Naik, Chandan, Sheth and Shah3,Reference Wang, Zhang, Zi and Xu4} While CT and MRI are useful for characterising cystic lesions and assessing their relationship to surrounding structures, the definitive distinction is often made intraoperatively. In our case, the cyst was found to be located on the epicardial surface with intimate coronary artery involvement, similar to the epicardial cysts described by Wang et al. ^{Reference Wang, Zhang, Zi and Xu4}

The surgical management of pericardial and epicardial cysts varies depending on their size, location, and relationship to vital cardiac structures. Reported cases have been managed through complete surgical excision via median sternotomy or video-assisted thoracoscopic surgery. ^{Reference Wang, Zhang, Zi and Xu4,Reference Kim, Kim, Choi and Jeong5} However, when cysts are intimately associated with coronary arteries or cardiac chambers, complete excision may not be feasible without risking significant complications. In the case reported by Gupta et al., an epicardial cyst was found to be eroding into the left ventricular wall, necessitating cardiopulmonary bypass for safe resection and reconstruction of the attenuated ventricular wall. ^{Reference Gupta, Shah, Naik, Chandan, Sheth and Shah3} Gupta et al. emphasised that cardiopulmonary bypass may be required when cysts compress surrounding structures or erode the ventricular wall and coronaries, and suggested that the surgeon must be aware of the possible need for cardiopulmonary bypass in such situations. Similarly, Wang et al. reported an epicardial cyst originating from the roof of the left atrium, which was successfully resected using an off-pump technique after careful assessment of coronary artery involvement. ^{Reference Wang, Zhang, Zi and Xu4} They emphasised that coronary CT angiography or coronary angiography should be considered based on the degree of adhesion and location of coronary vessels, and that when invasion of important structures, including the left ventricle and coronary artery, is suspected, median sternotomy with cardiopulmonary bypass should be considered.

These cases highlight the importance of thorough preoperative evaluation, particularly with coronary angiography or coronary CT angiography, to assess the relationship between the cyst and coronary vessels. ^{Reference Gupta, Shah, Naik, Chandan, Sheth and Shah3,Reference Wang, Zhang, Zi and Xu4} In our case, preoperative imaging suggested close proximity between the cyst and the right coronary artery, which was confirmed intraoperatively. The decision to leave a portion of the cyst unresected was made to preserve coronary artery integrity, as complete excision would have required extensive dissection along the right coronary artery with potential risk of arterial injury or compromise. This approach is supported by Wang et al., who noted that video-assisted thoracoscopic surgery/thoracotomy may be the first option, but when invasion of important structures is suspected, median sternotomy with cardiopulmonary bypass should be considered, and off-pump resection may be indicated for uncomplicated cysts. ^{Reference Wang, Zhang, Zi and Xu4}

Similar to the case reported by Masuoka et al. ^{Reference Masuoka, Sakurai, Shiraishi, Yoshiba, Katogi and Suzuki6} our patient presented in early infancy with symptomatic compression of cardiac structures. However, unlike their case, which presented as acute cardiac tamponade after chest trauma, our patient demonstrated progressive symptoms due to gradual cyst enlargement. The presence of concurrent pulmonary valve stenosis in our patient added complexity to the surgical management. While some reports have described isolated pericardial cyst resection, our case required combined procedures including cyst excision, pulmonary valve commissurotomy, and pulmonary artery augmentation. The decision to proceed with median sternotomy rather than video-assisted thoracoscopic surgery was influenced by the need for concurrent cardiac procedures and the anticipated complexity of dissection near the right coronary artery.

Regarding the natural history and recurrence risk of pericardial cysts, a retrospective observational study following 103 patients with confirmed pericardial cysts found that cysts most often regressed in size or remained the same, and those that grew required only continued monitoring due to asymptomatic presentations. ^{Reference Alkharabsheh, Ayache and Halabi7} Incomplete excision may have led to early recurrence, as documented in a recent case report where a pericardial cyst recurred within 5 months after surgical resection. ^{Reference Bachu, Mcdonald, Mandak, Moritz, Mandak and Murthy8} After recurrence, given further imaging suggesting that complete excision of the cyst would potentially injure nearby structures, repeat surgery was not recommended in that case, and fortunately, the patient reported no symptoms. Similarly, in our case, the intentionally retained cyst remnant adjacent to the right coronary artery necessitates close long-term follow-up with serial echocardiography to monitor for potential recurrence while balancing the risk of surgical complications against the benefits of complete excision.

This case underscores several important clinical lessons. First, pericardial cysts detected prenatally should be monitored closely for progressive enlargement and compression of cardiac structures. Second, comprehensive preoperative evaluation, including coronary artery assessment, is essential for surgical planning, particularly when cysts are located on the epicardial surface. Third, when complete excision poses excessive risk to vital structures such as coronary arteries, subtotal resection with cavity obliteration represents a reasonable alternative strategy. Finally, a flexible surgical approach with cardiopulmonary bypass standby should be considered for complex cases involving coronary artery proximity or concurrent cardiac lesions requiring repair.