Relationship between craniopharyngioma and the third ventricle floor meninges based on QST classification

Objective To explore the relationship between craniopharyngioma based on QST classification with invovlement of the third ventricle floor and the third ventricle floor meninges and its clinical significance. Methods The clinical data of 17 primary craniopharyngioma patients with involvement of the third ventricle floor (6 cases of Q type, 3 cases of S type and 8 cases of T type) undergoing total tumor resection under neuroendoscopy from January 2018 to October 2019 at Neurosurgery Department of Nanfang Hospital, Southern Medical University were retrospectively analyzed. Tumor tissue samples were taken from all patients during operation. The specimens of the normal sellar region were derived from the fetus (8 cases) of the artificial or spontaneous abortion at Nanfang Hospital of Southern Medical University during the same period. Samples were stained by hematoxylin eosin (HE) and immunofluorescence double staining. The dura was labelled with vimentin antibody, arachnoid with type I collagen antibody, pia with glial fibrillary acidic protein antibody and laminin antibody, adenohypophysis with CK18 antibody and craniopharyngioma with CK5 / 6 antibody. We then observed the meningeal staining of fetal brain tissue and relationship between different QST types of craniopharyngioma tissue and the third ventricle floor meninges. Results The dura mater, arachnoid and pia mater of 8 fetuses were labelled successfully. HE staining and immunofluorescence double staining of craniopharyngioma showed that in type Q tumor (6/6), there were dura mater (diaphragma sellae) between tumor and the third ventricle floor. In type S tumor (3/3), there were arachnoid membrane and pia mater between tumor and the third ventricle floor. There were 3 patterns regarding the relationship between type T tumor and the third ventricle floor: mantle-like relationship, moat-like and mortise-like types. There was pia mater between type T tumor (8/8) and the third ventricle floor, and the pia mater could gradually disappear at the origin point of tumor. Although the tumor could remarkably compress the third ventricle and occupy the space of ventricle, the ependymal layer of the third ventricle remained intact. Conclusions All QST types of craniopharyngioma could involve the third ventricle floor and there are various membrane layers between tumor and the third ventricle floor, which could provide natural interface for safe removal of craniopharyngioma with the third ventricle floor involvement. Key words: Craniopharyngioma; Third ventricle; Sella turcica; Meninges; Pathology