Microsurgical resection of a pure third ventricular craniopharyngioma through an interhemispheric transcallosal transforaminal approach.

Background: Craniopharyngiomas account for approximately 2-4% of all intracranial tumors and demonstrate a bimodal age distribution, typically affecting children aged 5-9 years and adults aged 55-69 years. Third ventricular craniopharyngiomas are rare, benign epithelial tumors that may arise primarily within the third ventricle or secondarily extend from the suprasellar region; the purely intraventricular subtype is particularly rare, with a reported incidence ranging from 0.5% to 14% of all cases. Despite benign histology, infiltration of adjacent neural tissue imparts clinically aggressive behavior and complicates complete resection. Their deep location near the hypothalamus, optic apparatus, and fornices poses major surgical challenges, and transcallosal approaches risk cognitive or memory deficit. A purely third ventricular craniopharyngioma, classified as Type D by Yaşargil and Type IV by Kassam, is confined to the third ventricle and is not accessible through an endonasal approach, making transcranial routes more suitable given the tumor's deep location and proximity to critical neurovascular structures, although select cases of successful endonasal resection have been reported. Case Description: We present a 34-year-old woman with galactorrhea and progressive weight gain over 6 months, together with intermittent diplopia and headaches. Magnetic resonance imaging demonstrated a homogeneously contrast-enhancing mass occupying the third ventricle, measuring 3.0 × 2.9 × 2.3 cm, with preservation of the pituitary stalk and third ventricular floor, causing moderate obstructive hydrocephalus. An interhemispheric transcallosal transforaminal approach was performed, with the dural opening adjusted according to the drainage pattern of the bridging veins, a 1.5 cm callosotomy, and septal fenestration. Gross total resection was achieved with preservation of the pituitary stalk, and a third ventriculostomy was performed to allow cerebrospinal fluid flow. Postoperative magnetic resonance imaging confirmed complete resection, and histopathological examination confirmed a World Health Organization Grade I papillary craniopharyngioma. Surveillance imaging at 27 months confirmed tumor recurrence, and the patient was referred for radiation therapy, after which no further recurrence was observed. Follow-up imaging at 48 months demonstrated continued absence of disease. Conclusion: Although there are reports of purely intraventricular craniopharyngiomas resected through the endonasal route, traditional transcranial approaches remain the standard for tumors located entirely within the third ventricle. Although this case was treated before routine molecular testing and targeted therapy became standard, modern management now requires a multidisciplinary strategy integrating microsurgery, radiotherapy, and targeted therapy with BRAF (B-Raf proto-oncogene, serine/threonine kinase) and MEK (mitogen-activated protein kinase kinase) inhibitors when appropriate.