Intravenous sinus meningioma with intraluminal extension to the internal jugular vein: case report and review of the literature.

Background: Meningiomas often invade venous sinuses, but intravenous sinus meningiomas remain within the intracranial cavity. This case report describes an extremely rare case of tentorial meningioma with venous sinus invasion, extending intraluminally into the lower part of the internal jugular vein in a 59-year-old man.Case presentation: The patient's initial surgery involved the supratentorial component of a right tentorial meningioma, which invaded the right transverse and sigmoid sinuses. The supratentorial component of the tumour did not enlarge during the 2-month waiting period for the first surgery. The patient received postoperative radiation therapy for the residual tumour in the intravenous sinus. Despite radiation, the residual tumour developed caudally and ultimately extended into the right internal jugular vein. The average regrowth speed of the extracranial mass was 3.6 mm/month. The patient underwent surgery for the recurrent tumour located in the transverse sinus, sigmoid sinus, jugular bulb, and internal jugular vein, 46 months after the initial surgery. The pathological features of both surgeries were the same; WHO grade I meningothelial meningioma.Conclusions: To the best of our knowledge, there have been few case reports of benign meningioma with intraluminal extension into the internal jugular vein, and there have been no reports of long-term observation of such cases. Detailed observation of the present case suggests that the difference in growth speed between the intracranial and venous cavity depends on the surrounding environment.