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canp2019c04

Case 4

R Van Ommeren, U Bartels, B Ertl-Wagner, A Kulkarni, C Hawkins

SickKids, University of Toronto

This previously healthy 14-year old right-hand dominant patient presented with 18 months duration of intermittent headaches, 2 months of gait imbalance and diplopia, and progressive difficulties with right hand co-ordination. 1 week prior to admission he additionally developed episodic nausea/vomiting, particularly after eating meals. Initial neurological examination revealed difficulties with tandem gait and toe-walking on the right side. Testing of cranial nerves showed nystagmus with lateral gaze, and diplopia at neutral ocular position exacerbated on downward and left lateral gaze. Finger-to-nose testing showed mild right sided dysmetria. An MRI scan was obtained which showed a large, expansile lesion centered in the left postero-lateral aspect of the pons. Notable features included heterogenous solid rim enhancement in the posterior aspect of the lesion, effacement of the fourth ventricle and mesencephalic cisterns, herniation of cerebellar tonsils through foramen magnum, and presence of a syrinx with multiple septations extending from C4 to C8. Stereotactic needle biopsy of the lesion was achieved through a left trans-cerebellar approach, and submitted to pathology.

Materials submitted: one representative H&E stained section

Questions:

1. What is the morphologic (differential) diagnosis for this lesion?

2. Which IHC/molecular studies would be appropriate given the clinical and demographic features of this case?