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SEER Inquiry System - Report
Produced: 01/15/2026 5:34 PM
Question 20041069
Inquiry Details
References:
WHO Class Nervous Sys Tumors, 180. 2000
Question:
Reportability--Brain and CNS: Is a meningioma invading the bone malignant and, therefore, SEER reportable if diagnosed prior to 2004? See Discussion.
Discussion:
1. Meningothelial meningioma with prominent nuclear pleomorphism, infiltration into dura, calvarium, temporalis skeletal muscle.
Microscopic: Multifocal infiltration by meningothelial tumor...extensive infiltration of trabecular spaces, extension through inner and outer calvarial layers by meningioma...mitotic activity in tumor noted but below the 4 per 10 high power field threshold for diagnosis of atypical meningioma.
2. Aggressive (invasive) transitional type meningioma, neuroimaging and histology imply extensive invasive meningioma involving bone and paraspinal soft tissues. Microscopy:...invaded bone...focal EMA positivity diagnostic of invasive transitional type meningioma... tumor invades bone.
Answer:
The two cases above are benign meningiomas and not reportable prior to 2004. According to an expert consultant, meningiomas are in the lining cells for the inner table of the skull and as such have an affinity for bone that allows them to penetrate adjacent bone without being "malignant."
The WHO Nervous System Tumor Classification states malignant meningioma exibits histological features of frank malignancy far in excess of the abnormalities present in atypical meningioma (WHO grade II). Examples of the histologic features of malignant meningioma are obviously malignant cytology, or high mitotic index (20 or more mitoses per 10 high-power fields). They correspond to WHO grade III and are usually fatal.
