GPR: 2021 - Week 09

From MGH Learn Pathology

Clinical history

23M with 8 month history of progressive dysconjugate gaze and ataxia with solitary mass lesion on imaging. Findings at autopsy are shown.


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Diffuse Midline Glioma, H3K27M Mutant
  • Infiltrative midline glioma most commonly arising in the pons, thalamus or spinal cord
  • Highly infiltrative, expansile, variably necrotic lesion generally diagnosed on imaging
  • Both children and adults affected; more common in children
  • K27M mutation in H3F3A or HIST1H3B / HIST1H3BC is defining genetic feature



Metastatic melanoma

  • Common sites are cerebral hemispheres, cerebellum, but can occur in brainstem, spinal cord, sella, and choroid plexus
  • Well-defined, firm, often hemorrhagic lesions
  • Tend to present in advanced disease with seizures, site-specific mass effects, or nonlocalizing signs




  • Circumscribed glioma with ependymal differentiation
  • Most commonly arise along the ventricular system in the posterior fossa, particularly in children
  • CNS parenchymal invasion is rare
  • Typical presentation: obstructive hydrocephalus from posterior fossa mass effect




  • Can occur as primary CNS lymphoma, or as secondary involvement
  • Single/multiple masses, typically in cerebral hemispheres, often adjacent to ventricular system
  • Variable macroscopic appearance, from well-demarcated to nearly indistinguishable
  • Presentation more commonly features cognitive dysfunction, focal deficits.
Melanie Lang-Orsini

Samantha Champion

Prior MGH neuropathology fellows
  • David N. Louis, Hiroko Ohgaki, Otmar D. Wiestler, Webster K. Cavenee (Eds):

WHO Classification of Tumours of the Central Nervous System (Revised 4th edition). IARC: Lyon 2016.

This week's Gross Pathology Roundup was presented by Christopher Mount, MD, PhD on Mon, Mar 01, 2021.