Posterior mediastinal Müllerian cysts: a single-center retrospective analysis

Posterior mediastinal Müllerian cysts are rare cystic lesions typically occurring in women in their 40s to 60s and located in the paraspinal region. Evidence is mainly limited to case reports, and their anatomical characteristics and pathological basis for localization remain poorly understood. This study aimed to investigate the anatomical features of these cysts and the relationship between operative and pathological findings.

This single-center retrospective analysis included seven patients who underwent surgical resection and were pathologically diagnosed with posterior mediastinal Müllerian cysts between January 2010 and December 2024. Clinical, imaging, intraoperative, and pathological findings were reviewed, with particular attention to lesion location, dissection characteristics, and histological findings.

All patients were women, with a median age of 45 years. All lesions were located in the paraspinal region and appeared as smooth-marginated, unilocular cystic lesions on imaging. Intraoperatively, all lesions were thin-walled cysts containing clear fluid. Blunt dissection was feasible along surfaces adjacent to surrounding structures, including the aorta and azygos vein, whereas sharp dissection was required along the vertebral body (VB) surface. Histopathological examination demonstrated dense fibrous connective tissue immediately adjacent to the cyst wall, separated only by a thin layer of relatively loose connective tissue.

Posterior mediastinal Müllerian cysts are thin-walled cystic lesions with a characteristic paraspinal distribution and no apparent continuity with surrounding organs. The requirement for sharp dissection adjacent to the VB may reflect the close anatomical relationship between the cyst wall and the fibrous connective tissue overlying the VB.