Case Study 27
Julia Kofler, M.D.
Question 1
A 5-year-old girl presents with a ~6 week history of early
morning headaches. Describe the findings in her MRI
scan.
T1
T1 plus
contrast
T1 plus
contrast
Answer
 Large mixed cystic and solid midline mass in the
posterior fossa
 Inhomogeneous contrast-enhancement of the solid
component
 Mass effect with displacement of the brainstem
 Obstructive hydrocephalus
Question 2
What is your major differential diagnosis for posterior
fossa tumors in children?
Answer
 Ependymoma
 Pilocytic astrocytoma
 Medulloblastoma
Question 3
An intraoperative consultation was requested and
performed via telepathology. Describe the findings in the
intraoperative smear preparation on the following
representative snapshots obtained via the telepathology
system.
Answer
 Hypercellular smear
 “Small round blue cells” with scant cytoplasm, finely
speckled chromatin and inconspicuous nucleoli
 No glial processes apparent
 Numerous mitotic figures and apoptotic bodies
Question 4
What is your intraoperative diagnosis?
Answer
Medulloblastoma
Question 5
A resection of the mass was performed. Describe the
findings in the following representative permanent H&E
slide.
Click here to view slide.
Answer
 Densely packed round to oval cells with high N/C ratio,
scant cytoplasm and inconspicuous nucleoli
 Occasional nuclear molding
 Frequent apoptotic cells and scattered mitoses
 Multiple foci of necrosis
 Scattered Homer Wright rosettes
 Large areas with a nodular appearance; nodules
display decreased cellular density, reduced N/C ratio
and a fibrillary matrix
 No anaplastic features are present
Question 6
Identify the rosette types in the following images and give
example(s) of tumors where these rosettes can be found.
A
Image sources:
Ellison and Love, Neuropathology, 2nd ed, 2007
Wippold and Perry, Am J Neuroradiol 2006; 27:488-492
B
C
D
Answer
A. Pseudovascular pseudorosette: Ependymoma,
glioblastoma, medulloblastoma, PNET, pilomyxoid
astrocytoma
B. Flexner Wintersteiner rosette: Retinoblastoma,
pineoblastoma
C. Ependymal rosette: Ependymoma
D. Homer Wright rosette: Neuroblastoma,
medulloblastoma, PNET, pineoblastoma
Question 7
Medulloblastomas can present with distinct
histopathologic subtypes.
1)Name major histopathologic subtypes
2)Which is the predominant subtype in our case?
3)Which stains can be used to highlight this growth
pattern in our case?
Answer
1) - Desmoplastic/nodular medulloblastoma
- Medulloblastoma with extensive nodularity
- Anaplastic medulloblastoma
- Large cell medulloblastoma
- Medulloblastoma with myogenic differentiation
- Medulloblastoma with melanotic differentiation
2) Desmoplastic/nodular medulloblastoma
3) Synaptophysin, reticulin, Ki-67
Question 8
Describe the findings in the following
immunohistochemical slides for synaptophysin and Ki-67.
Click here to view slide
(GT.59B synaptophysin, GT.59C Ki-67).
Answer
 Synaptophysin is positive within the nodular areas
indicating regions of neuronal maturation
 Ki-67 shows high proliferative activity in the
internodular areas and lower proliferation rates within
the nodules
 These stains support a diagnosis of
desmoplastic/nodular medulloblastoma
Question 9
Name clinical, pathological and molecular factors that
have been associated with adverse or favorable outcome
of medulloblastomas.
Answer
 Adverse outcome:





Age <3 years
Incomplete surgical resection
Metastatic disease
Large cell/anaplastic variant
Isochromosome 17q, loss of 17p, amplification of
MYCC or MYCN genes
 Favorable outcome:
 Desmoplastic/nodular variant
 Nuclear accumulation of beta-catenin
Question 10
Which familial cancer predisposition syndrome is
associated with the desmoplastic/nodular variant of
medulloblastoma?
Answer
Naevoid basal cell carcinoma syndrome (Gorlin
syndrome)