Philip, Sarah MSJaved, MadeehaLachowsky, ParkerKaragoli, MustafaHutton, SarahLe, MinhJung, Esther MSKao, Jeremy2019-08-222019-08-222019-03-052019-02-05https://hdl.handle.net/20.500.12503/27427Abstract Background: Pericardial cysts are usually benign, congenital or idiopathic anomalies with an occurence of 1:100,000 and are commonly noted in the right (70%) or left (22%) cardiophrenic angle and are rarely found in other locations of the pericardium, such as the anterior or posterior superior mediastinum (8%). The aortopulmonary window is the small space between the aortic arch and the pulmonary artery that holds the ligamentum arteriosum, recurrent laryngeal nerve, and lymph nodes. It is a common location for lymphadenopathies, but is a less common location for tumors, cysts, or aneurysms, further signifying the rarity of our findings. Case Information: During a routine dissection of a 91-year-old female cadaver, a pericardial cyst was noted in the aortopulmonary window, an unusual location for such cysts. Conclusion: This case report serves to expand knowledge on the anatomical aspects of rare pericardial cyst locations. Pericardial cysts are often asymptomatic and incidental findings, but some patients may present with complications consisting of dyspnea, cough, and hemoptysis secondary to the compression of structures surrounding the cyst. Knowledge of rare pericardial cyst locations is necessary for clinicians and surgeons during diagnostic and therapeutic procedures, and as a result, current clinical guidelines should take rare variants into consideration.enposter