Answer and Discussion of Quiz Set: N-027

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

A.  Meningiomas are negative for cytokeratin.

B.  S100 protein may have a patchy immunoreactivity in meningiomas.

C.  Psammomatous meningiomas are WHO grade I tumor if there is no histologic features indicative of aggressive behavior or malignancy behavior.

D.  Interdigitating cytoplasmic process is one of the ultrastructural features of meningiomas.

E.  Meningiomas are typically contrast enhancing.

Answer and Discussion: The answer is (A). Occasional positivity for cytokeratin can be seen in meningioma as well as patchy immunoreactivity for S100 protein. However, if there is strong and extensive positivity for cytokeratin, the possibility of a metastatic carcinoma must be strongly entertained. Interdigitating cytoplasmic processes and membrane junctional complex are ultrastructural features of meningiomas which are helpful diagnostic aids.