The pineal cell lobules and their surrounding astrocytes, which constitute the main body of the pineal gland, and the ventricular canal of the third ventricle located anterior to the pineal gland, can be tumorigenic:Summary of Pathologic Findings in 191 Patients Undergoing Surgery for Pineal Region Tumors at the New York Neurological Institute (1981-2001) Tumor Pathologic Type No. Germ Cell 62 (32%) Germinoma 30 Teratoma 9 Lipoma 2 Epidermoid 1 Mixed malignant germ cell 16 Immature teratoma 2 Embryonal cell carcinoma 2 Pineal Cell 48 (25%) Pineocytoma 27 Pineoblastoma 11 Mixed pineal cell 10 Glial Cell 52 (27%) Astrocytoma 27 Anaplastic astrocytoma 3 Glioblatoma 4 Ependynoma 14 Oligodendroglioma 2 Choroid plexus neoplasms 2 Miscellaneous 29 (15%) Pineal cyst 9 Meningioma 10 Other malignant and benign 5+4 HCG and AFP for diagnostic guidance: HCG: Tumor must be choriocarcinoma or germ cell tumor combined with syncytial trophoblastic giant cell component. Serum HCG > 2000 mIU/ml for choriocarcinoma; and serum HCG < 1000 mIU/ml for germ cell tumors with a syncytial trophoblastic giant cell component AFP: The tumor must be an endothelial sinus tumor (yolk sac tumor) or a germ cell tumor with a syncytial sinus tumor component. If AFP and HCG are negative, the tumor may be germ cell tumor, embryonal carcinoma, mature teratoma, naïve teratoma, malignant teratoma, germ cell tumor mixed with other components, pineal parenchymal tumor (pineal tumor, pineoblastoma, pineal tumor combined with lymphocytic infiltration). Pure embryonal carcinoma without combined endothelial sinus tumor or choriocarcinoma components can be negative for both AFP and HCG, but is very rare. If 20Gy radiotherapy is effective in reducing the tumor size, it indicates that the tumor is a germ cell tumor or a pineal tumor derived from 2 cellular components combined with lymphocytic infiltration. However, if the tumor is larger than 2 cm in diameter (sometimes 1.5 cm), direct resection of the tumor followed by radiotherapy is recommended. Surgical modality: open resection of the tumor: allows to obtain a large number of specimens or even total resection of the tumor, very important for the diagnosis of tumors in the pineal region, where there are many mixed tumors; cures benign tumors; improves the effectiveness of radiotherapy and improves the long-term prognosis. Disadvantages: high recent mortality and disability associated with surgery. Stereotactic biopsy: suitable for patients with multiple lesions that cannot tolerate surgery; however, the surrounding structures are complex, vascular and risky. Endoscopic biopsy or resection of tumor: suitable for triple ventriculostomy with simultaneous tumor biopsy, but requires a flexible scope. Operative mortality: 0-8%; permanent disability: 0-25%; mainly related to the texture of the tumor, blood supply, and the operator's experience and microscopic operating skills. Complications: Bleeding: intraoperative or postoperative, mostly in pineoblastoma, with soft, vascular tumors Abnormalities of the pupil (tetanus); impaired consciousness (brainstem); transient loss of union syndrome (involuntary, uncontrollable, purposeless movements of one upper limb or hand, accompanied by the patient's unfamiliarity and anthropomorphism of his affected limb. ); transient near-memory deficits; transient muteness; visual field deficits. Typical case 1: Before and after surgery Typical case 2: Before and after surgery