Clinical Features, Radiologic Findings, and Surgical Outcomes of 65 Intracranial Psammomatous Meningiomas

OBJECTIVE: Intracranial psammomatous meningiomas (PMs) are rarely reported due to their extremely low incidence. Knowledge about intracranial PMs is therefore poor. This study aimed to analyze the incidence, clinical features, radiologic findings, and surgical outcomes of intracranial PMs. METHODS: Approximately 5651 intracranial meningiomas were surgically treated at Beijing Tiantan Hospital between November 2011 and December 2015. The authors identified all cases in which patients underwent resection of an intracranial tumor that was found to be a PM on pathologic examination and analyzed the data from these cases. RESULTS: PMs accounted for 1.15% of the entire series of intracranial meningiomas. Sixty-two (95.4%) of these 65 intracranial PMs were female. The median maximal tumor diameter was 2.8 cm (range, 1.4-8.4 cm). On computed tomography scan, all PMs (23/23) showed various calcification. Gross total resection was achieved in 56 cases, near total resection in 5, subtotal resection in 3, and partial resection in 1. Seventeen (26.2%) of the patients experienced new or exacerbated deficits immediately after operation. Three patients (17.6%, 3/17) got alleviation when assessed at last follow-up. Eleven patients (16.9%) experienced additional surgical complications. At the time of discharge, Karnofsky Performance Scale (KPS) score and neurologic function showed improvement in 50 cases (76.9%) and worsening in 15 cases (23.1%). At a median follow-up of 37 months (range, 7-56 months), 1 patient had experienced tumor regrowth 50 months after surgery and the 4-year progression-free survival rates were 100.0%. No patient died of recurrence. At the latest follow-up, the KPS score showed improvement in 56 cases (86.2%) and worsening in 9 cases (13.8%). Tumor located in the skull base is significantly associated with an increased risk of worsened long-term outcomes. Preoperative KPS score < 90, peritumoral brain edema (PTBE), and hypointensity on T2-weighted imaging had a statistically significant effect on the extent of tumor resection. CONCLUSIONS: Intracranial PM is a rare subtype of meningioma with marked female predominance and low tendency toward growth and recurrence. Most intracranial PMs exhibit highly calcified imaging characteristics, particularly as seen by computed tomography. Microsurgical treatment of skull base PM remains a formidable challenge due to the hard tumor consistency and critical neurovascular structure encasement. It is unnecessary for radical tumor resection at the cost of severe neurologic deficits.