The brain being illustrated was taken from a 8 year-old child. What is your gross pathologic diagnosis?

A.  Meningioma

B.  Pilocytic astrocytoma affecting the optic chiasma

C.  Pituitary adenoma

D.  Resolved pontine infarction

E.  Diffuse infiltrating pontine glioma

Answer and Discussion: The answer is (E). The brainstem in particularly the pons is diffusely and roughly symmetrically enlarged. This is most consistent with an expansive lesion diffusely involving the pons and in this case the most probably diagnosis is diffuse infiltrating pontine glioma (DIPG). In general, the prognosis of DIPG is grave. Although infarction of the pons can occur in infants and children and the early phase would lead to edema and expansion of the pons, resolved pontine infarction would be characterized by a collapsed and distorted pons.

Pilocytic astrocytoma affecting the optic nerves and/or optic chiasma can occur in children with neurofibromatosis 1 (NF1). However, the optic nerves and chiasma are in pristine condition in this case. Can you find these structures?  The pituitary gland is not included in this image and therefore there is no way to tell if there is a pituitary adenoma. The pituitary stalk, however, is grossly unremarkable. Meningioma typically, but not always, occur as an extra-axial mass which means that they are separated from the brain parenchyma. It is clearly not the case in this specimen.