Answer and Discussion of Quiz Set: N-027

1.    Which of the followings is not true about meningioma?

A.  High mitotic rate (4 per 10 high power fields) is one of the diagnostic criteria for atypical meningioma (WHO grade II).

B.  Brain invasion is one of the diagnostic criteria for atypical meningioma (WHO grade II).

C.  Invasion into adjacent bone  is one of the diagnostic criteria for atypical meningioma (WHO grade II).

D.  Papillary meningioma and rhabdoid meningioma are anaplastic meningiomas (WHO grade III).

E.  Meningiomas are positive for epithelial membrane antigen (EMA).

Answer and Discussion: The answer is (C). While invasion into brain is a criterion for the diagnosis of atypical meningioma, invasion into adjacent bone is not one of the diagnostic criteria for atypical meningioma. Meningiomas arising in the cranial base has a strong tendency to invade into the cranial base. They may extend into the paranasal sinuses, orbit, and invade into the upper jaw. Clinical manifestations may include obstruction of nasal sinuses and dental pain.