Enterogenous cysts of the spinal canal and cerebellopontine angle

Enterogenous cysts are rare, benign lesions involving the spinal canal or the cerebellopontine angle. Typically they present with compression of the spinal cord or cranial nerves. They are usually 1 cm or less in size and are typically lined by columnar mucin-producing epithelium resembling enteric epithelium or columnar ciliated epithelium resembling respiratory epithelium. The case records of the Division of Neuropathology at Indiana University were reviewed for cystic lesions of the spinal canal and cranial cavity for a 26-year period. Seven surgically resected enterogenous cysts were identified. The original slides were studied. Additional sections were stained with mucicarmine, and immunohistochemical stains including thyroid transcription factor 1, epithelial membrane antigen, and cytokeratin 5/6 (CK5/6) were performed. Electron microscopy was performed in 1 case. The cysts ranged in size from 4 to 10 mm. One had stratified cuboidal epithelium, 1 had ciliated columnar and stratified squamous epithelium, 1 had columnar mucinous epithelium, and 4 had ciliated columnar epithelium. Epithelial membrane antigen and CK5/6 positivity were observed in all cases. Strong CK5/6 positivity was seen in the basal cells, with little or no immunoreactivity in the ciliated cells. Mucicarmine positivity was observed in 4 cases, and thyroid transcription factor 1 positivity was observed in 2 cases. Electron microscopy demonstrated well-developed stereocilia, distinct basal cells, and a thin basement membrane. The histopathologic, ultrastructural, and immunologic findings in these lesions are similar to those present in the bronchial epithelium, supporting the hypothesis of endodermal origin for these lesions.