Answer and Discussion of Quiz Set: N-001

5.    Which of the following is not true?  Answer

A.  The highest incidence of germ cell tumor in the brain is pineal followed by the pituitary gland area.

B.  Interphotoreceptor retinoid-binding protein (IRBP) is positive in pineal parenchymal tumors and retinoblastomas but negative in medulloblastomas.

C.  Pineal parenchymal tumor of intermediate differentiation belongs to WHO grade II and grade III.

D.  Giant rosette is a feature of pineocytoma.

E.  In human, the pineal reaches its adult size at about 2 years old

Answer and Discussion: The answer is (B). Although pineal parenchymal tumor are typically positive for photoreceptor markers such as IRBP, medulloblastoma are also positive for these markers in many cases. The human pineal gland reaches it adult size at around 2 years of age.

References:

1.       Korf HW, Korf B, Schachenmayr W, Chader GJ, Wiggert B., Immunocytochemical demonstration of interphotoreceptor retinoid-binding protein in cerebellar medulloblastoma., Acta Neuropathol. 1992;83(5):482-7.

2.       Sumida M, Barkovich AJ, Newton TH. Development of the pineal gland: measurement with MR. AJNR Am J Neuroradiol. 1996 Feb;17(2):233-6.