Primary ependymoma in the posterior mediastinum.

A 46-year-old woman was referred to our hospital because of back pain and an abnormality on chest imaging. Chest computed tomography showed a well-delineated tumor in the left paravertebral space. Histological analysis of the resected tumor revealed perivascular pseudorosettes, and immunoreactivity for glial fibrillary acidic protein established the diagnosis of ependymoma. A few cases have been reported in the ovary, broad ligament, sacrococcygeal region, lungs, and mediastinum, but the pathogenesis has not yet been clarified. Female predominance in these tumors and organogenesis of the sites may suggest a key to the pathogenesis.