A 6 year old male presents with "awkward walking" and headaches for the past 4 months. The mother states that he can not walk straight and has occasionally walked into walls. In the past month he has experienced nausea and vomiting. On physical exam he exhibits normal tone and strength in all four limbs with normal symmetric muscle stretch reflexes. There is bilateral papilledema and marked truncal ataxia. Vital signs are normal. Laboratory values reveal a normal CBC, U/A, lytes, glucose and calcium.

1. Based on the above information, the next step in the management of the patient is:

A. perform a spinal top

B. obtain an MRI or CT-scan of the head and neck

C. obtain an EEG

D. obtain visual evoked reponses (VER)

E. order nerve conduction studies and EMG

F. C and D

Correct Answer: B

An EEG showed diffuse slowing. CT of the head and neck show the following:

A biopsy is obtained, shown in the following image:

2. Based on the history, physical, biopsy and CT findings, the most likely diagnosis is:

A. epidermoid cyst

B. pleomorphic xanthoastrocytoma

C. brain stem glioma

D. medulloblastoma

E. chordoma

Correct Answer: D

3. Based on the history, physical and CT findings in this patient, the following tumor would also be in the differential diagnosis:

A. epidermoid cyst

B. primary brain lymphoma

C. germ cell tumor

D. pleomorphic xanthroastrocytoma

E. pilocytic astrocytoma

Correct Answer: E

4. The following statement(s) is/are true:

A. 95% of childhood brain tumors are medulloblastoma.

B. Psammoma bodies are not typically found in meningioma.

C. Medulloblastomas are radiosensitive tumors.

D. Brain stem gliomas are usually seen in elderly adults.

E. Craniopharyngiomas are found in the fourth ventricle.

Correct Answer: C

5. The following statement(s) is/are true:

A. Medulloblastoma represents approximately 20-25% of brain tumors in children.

B. The male to female ratio of medulloblastomas is approximately 2:1.

C. Patients with medulloblastomas may have genetic aberrations involving chromosome 17.

D. Medulloblastoma may disseminate directly through CSF producing spinal cord and cauda equine tumor nodules called "drop" metastases.

E. All of the above.

Correct Answer: E