[Anatomical variants of papillary craniopharyngiomas: analysis of surgical series].

Background: Craniopharyngiomas are benign tumors of the chiasmal-sellar region of adults and children, prone to local invasion and recurrence. There are two morphological types of craniopharyngiomas - adamantinomatous (in children and adults) and papillary (PCPs) (mainly in adults). PCPs are a rarer type (15-20%). In the literature of recent years devoted to PCPs, two main variants of these tumors are distinguished: 1) solid intraventricular (III ventricle) and 2) monocystic with a small tumor component located outside III ventricle.

Objective: To investigate the pathogenesis of PCPs and clarify the causes of formation of different anatomical tumor variants.

Material and methods: The study included 34 adult patients with PCPs, among them 21 - women and 13 - men, who had undergone primary surgical treatment in the NMRC for Neurosurgery named after Academician N.N. Burdenko from 2017 to 2024. The inclusion criterion was the presence of suprasellar, extra-intraventricular and strictly ventricular localization according to the brain MRI data. Tumor resection was performed using microsurgical (12) and endoscopic transsphenoidal access (22). In all cases, intraoperative sampling of histological material was carried out, including both a solid part of the tumor and a tumor cyst capsule. «Papillary craniopharyngioma» diagnosis in all cases was histologically confirmed.

Results: Two main forms of PCP have been identified - solid intraventricular PCP (III ventricle) (24%) and PCP with pronounced monocystic component (76%). Cystic PCPs of two variants - suprasellar extraventricular (cisternal) cystic PCPs and cystic PCPs, displacing the III ventricle's floor and spreading into its cavity.

Conclusion: The existence of two main forms of PCPs - solid intraventricular and predominantly cystic is determined by the initial tumor growth site relative to the pia mater. The cause for formation of cystic forms of PCPs is their location under the pia mater, which participates in the cystic wall formation.