[Clinicopathological analysis of pseudostratified ependymal tubules in ovarian mature teratoma].

Objective: To investigate the morphology and immunohistochemical (IHC) expression of pseudostratified ependymal tubules in ovarian mature teratoma (MT). Methods: Five cases of ovarian MT with pseudostratified ependymal tubules were collected from Shenzhen Hospital(Futian) of Guangzhou University of Chinese Medicine and the Eighth Affiliated Hospital of Sun Yat-sen University from March 2019 to March 2022. In addition, 15 cases of ovarian MT with monolayer ependymal epithelium from Shenzhen Hospital (Futian) of Guangzhou University of Chinese medicine and seven cases of immature teratoma (IMT) from Hainan Provincial People's Hospital from March 2019 to March 2022 were collected as control. The morphologic characteristics and immunophenotypes of pseudostratified ependymal tubules, monolayer ependymal epithelium, and primitive neural epithelial tubules were observed and compared by H&E stain and IHC expression pattern of genes related to the differentiation status of neuroepithelium, namely SALL4, Glypican3, nestin, SOX2, Foxj1, and Ki-67. Results: Mean age of the five patients of ovarian MT with pseudostratified ependymal tubules was 26 years (range from 19 to 31 years). Two tumors were located in the left ovary and three in the right. All five cases were excised, and clinical follow-up was available (mean follow-up 1.5 years; range 0.5 to 3 years). No recurrence was noted in any cases. The pseudostratified ependymal tubules of ovarian MT, which were lined with columnar or oval epithelia up to 4-6 layers, were morphologically similar to the primitive neuroepithelial tubules of IMT and different from monolayer ependymal epithelium of ovarian MT. By immunohistochemistry, SALL4 and Glypican3 were negative, Foxj1 was positive and Ki-67 index was lower in the pseudostratified ependymal tubules and the monolayer ependymal epithelium of ovarian MT. However, the primitive neuroepithelial tubules of IMT showed variably expression of SALL4 and Glypican3, were negative for Foxj1 and high Ki-67 index. All the above three groups expressed nestin and SOX2. Conclusions: The pseudostratified ependymal tubules of ovarian MT, which have morphological similarities to the primitive neuroepithelial tubules of IMT, are similar to the monolayer ependymal epithelia of the MT in immunophenotype. IHC assessment of Foxj1 and Ki-67 is helpful to differentiate the pseudostratified ependymal tubules of ovarian MT from the primitive neuroepithelial tubules of IMT.