Abstract #19

Presenter

My name is Kenrick Wysong and I am a first year pathology resident at the University of Vermont Medical Center. I am originally born and raised in California but recently moved to Burlington, Vermont for my residency. I received my B.S in Neuroscience from La Sierra University and MD from Loma Linda University School of Medicine in California.
I have always had an interested in how the human mind works and to understand its inner biochemistry. I originally considered Neurology but decided to pursue Pathology with the hope of eventually going into Neuropathology to pursue this interest. My goal is to eventually get a job where I spend my whole days looking and reading about at neurons in the future.

Authors

Kenrick Wysong MD, Matija Snuderl MD PhD, John C. DeWitt MD PhD

CanMEDS:
Medical Expert (the integrating role)

Extra-pineal papillary tumor of the pineal region (PTPR) masquarading as a subependymal giant cell tumor (SEGA)

Abstract

Papillary tumor of the pineal region (PTPR) is a rare neuro-epithelial tumor arising in the pineal region characterized typically by papillary and solid architecture with epithelial-like cells and reactivity for cytokeratins, while subependymal giant cell tumor (SEGA) is a periventricular tumor composed of large ganglion-like astrocytes.  Here we describe the case of 75-year-old man with a slowly enlarging superior cerebral aqueduct mass first discovered and followed over six years prior to biopsy.  Given its increasing size a small biopsy was performed which was characterized by large pleomorphic ganglion-like giant cells with abundant cytoplasm and prominent nucleoli.  Immunohistochemistry showed that tumor cells were strongly positive for S100, but negative for GFAP.  Despite the patient not carrying a diagnosis of tuberous sclerosis, given the ventricular location, histologic appearance, and immunohistochemical results a diagnosis of a low grade tumor consistent with subependymal giant cell astrocytoma (SEGA) was issued, with outside expert consultation in agreement with this interpretation.   Subsequently, despite surgery the mass continued to slowly grow over the next few years and the decision was made to perform next generation and methylation sequencing 4 years following the initial biopsy.   Next generation sequencing returned only the presence of an NF2 mutation, while methylation sequencing was a match for papillary tumor of the pineal region.  Subsequent immunohistochemistry for Keratin AE1/3 was strongly positive on the original biopsy, consistent with this new diagnosis.  This case demonstrates the utility of methylation sequencing, particularly when biologic behavior and sequencing results do not correlate with histologic diagnosis.