Multilocular Thymic Cyst Associated with Mediastinal Teratoma: A Case Report

Congenital cysts are typically unilocular and thin-walled to the point of translucency; careful histopathologic examination shows no evidence of inflammation. In contrast, acquired thymic cysts are usually multilocular, hence the commonly used term “multilocular thymic cyst (MTC).” These cysts have thick, fibrous walls, and histopathologic examination typically reveals significant inflammation and fibrosis (1-3). Multilocular thymic cyst can develop in concert with various mediastinal neoplasms including thymoma, thymic carcinoma, Hodgkin’s disease, and seminoma (1, 2). Two cases of MTCs associated with benign mediastinal teratomas have been reported, but to our knowledge, detailed CT features and CT-histopathologic correlations have not been described (1). Here, we report the findings of a case of MTC associated with mediastinal mature cystic teratoma on computed tomography (CT) with CT-histopathologic correlations.