GPR: 2021 - Week 09

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

Ependymoma

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

Lymphoma

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

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.