Presenter
John P. Rossiter
Bio
John Rossiter is a neuropathologist at Kingston Health Sciences Centre and a professor in the Department of Pathology and
Molecular Medicine, Queen’s University, Kingston, Ontario, Canada.
Authors
John P. Rossiter1, Shane E. A. Eaton2, Adrian B. Levine2
1Department of Pathology and Molecular Medicine, Queen’s University, Kingston, ON, and 2Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON.
Clinical Summary
A previously healthy 20 year old man presented following a de novo generalized seizure. Neuroimaging showed a partially calcified, non-enhancing, intracortical lesion (1.5 x 1.3 x 1.3 cm) in the right lateral occipito-parietal region. Following a gross total neurosurgical resection, the patient remains seizure-free.
Conflict of Interest
I do not have a relationship with a for-profit and/or a not-for-profit organization to disclose.
Discussion points
- What is the differential diagnosis based on H&E?
- What further investigations would likely be most diagnostically informative?
Reveal Diagnosis
Polymorphous low-grade neuroepithelial neoplasm of the young (PLNTY), CNS WHO grade 1, BRAF pV600E mutation by IHC
and NGS.
The initial histology favoured a low-grade neuroepithelial neoplasm with extensive microcalcifications, but a differential of ‘calcifying pseudotumour of the neuraxis’ was also considered.
The immunohistochemical profile included: GFAP and S100 strongly positive; CD34 regional strong staining of tumour cells; Olig2 positive; BRAF V600E focally positive; IDH1R132H negative; ATRX retained; Ki-67 ≤ 2%.
DNA methylation profiling classification: DKFZ v12.8: consistent with Ganglioglioma (score 0.7921); NIH Bethesda v2: Ganglioglioma (score 0.997); CNV summary: gain of chromosome 5, 6, 12, 15, 16, 19, 20.
Despite the methylation classification as ganglioglioma, a clear neoplastic neuronal component was not identified, within the limitation of a highly calcified lesion with a relatively small proportion of cellular elements. Given that PLNTY and ganglioglioma have very similar methylation profiles, the overall histologic features, including infiltrative growth, focal oligodendroglioma-like morphology, and CD34 expression, indicate a diagnosis of PLNTY.
References
1. Huse JT, Snuderl M, Jones DTW et al. Polymorphous low-grade neuroepithelial tumor of the young (PLNTY): an epileptogenic neoplasm with oligodendroglioma-like components, aberrant CD34 expression, and genetic alterations involving the MAP kinase pathway. Acta Neuropathol. 2017 Mar;133(3):417-429. doi: 10.1007/s00401-016-1639-9.
https://link.springer.com/article/10.1007/s00401-016-1639-9
2. Ida CM, Johnson DR, Nair AA et al. Polymorphous low-grade neuroepithelial tumor of the young (PLNTY): molecular profiling confirms frequent MAPK pathway activation. J Neuropathol Exp Neurol. 2021 Sep 27;80(9):821-829.doi: 10.1093/jnen/nlab075.
https://academic.oup.com/jnen/article/80/9/821/6345437?login=false
3. Gao A, Hazrati LN & Hawkins C. American Association of Neuropathologists, Diagnostic Slide Session 2017, Case 3.
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