A 55-year-old woman undergoes resection of a convexity dural-based mass. Microscopy shows spindle meningothelial cells in whorls with numerous concentric lamellated calcifications. Mitotic count is 1 per 10 high power fields and there is no brain invasion. What is the diagnosis and WHO grade?

• A Atypical meningioma, WHO grade 2
• B Psammomatous meningioma, WHO grade 1 ✓
• C Anaplastic meningioma, WHO grade 3
• D Solitary fibrous tumor of the meninges, WHO grade 1

Explanation

Whorls with abundant psammoma bodies define the psammomatous variant of meningioma, a benign WHO grade 1 tumor. Grade 2 (atypical) requires either 4 or more mitoses per 10 high power fields, brain invasion, or specific architectural patterns such as sheeting and macronucleoli. Grade 3 requires 20 or more mitoses per 10 high power fields or features of frank malignancy. Solitary fibrous tumor lacks whorls and psammoma bodies and is defined by STAT6 rearrangement.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.