CNS tumor
Grossing & features to report

Topic Completed: 1 January 2016

Minor changes: 26 February 2020

Copyright: (c) 2002-2020,, Inc.

PubMed Search: Gross [title] CNS tumor

Nat Pernick, M.D.
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Cite this page: Pernick N. Grossing & features to report. website. Accessed May 26th, 2020.
Definition / general
  • Evaluate the arachnoid, gray and white matter
  • Section, if possible, from the arachnoid through the gray to the white matter
  • Sample interface between the lesion and normal appearing brain
  • EM helpful for poorly differentiated or unusual tumors (clear cell ependymoma), toxic - metabolic disease, infection; recommended to save tissue for EM in challenging cases
  • Infarcts: section perpendicular to surface of brain, submit sections of arachnoid, gray and white matter; save gray matter for EM if considering CADASIL or mitochondrial disease
  • Hematopoietic lesions: also B5, cell culture media (for flow cytometry), touch preparations, flash frozen tissue for molecular analysis
  • Infectious disorders: recommended that surgeon obtain cultures from sterile operating field
  • Toxic - metabolic disorders: recommend fixation of gray and white matter in formalin, glutaraldehyde, frozen tissue bank

  • Margins: usually impossible to assess due to piecemeal nature of resection or infiltrative growth pattern; may be able to determine for childhood pilocytic astrocytoma of cerebellum, cerebral dysembryoplastic neuroepithelial tumor and meningioma

  • Safety: recommended that surgeon contact lab if patient is HIV+ (use cytology, not frozen section) or may have Creutzfeldt-Jakob disease (decline frozen sections since cannot decontaminate cryostat); decontaminate cryostat used for HIV+ tissue by replacing blade, removing frozen debris and wiping surfaces with 10% bleach in water; for CJD specimens that are sectioned, recommended to place cassettes in formalin for 24 hours, then transfer to 100% formic acid for one hour, then return to fresh formalin for 48 hours, then process; label cassettes with pencil (formic acid dissolves ink), wrap needle biopsies in lens paper, handled embedded tissue as if infectious, dispose of blade, section waste, wipe microtome and cutting station with bleach, incinerate all towels, gloves and waste

  • References: University of Pittsburgh: Neuropathology Grossing Manual
Gross features of various disease entities
  • Abnormal mass: solid tissue not identifiable as gray or white matter
  • Cyst wall: flat tissue from 0 to 3 mm thick - compare to surgeon's impression or radiographs
  • Gliosis: often yellow or gray and firm
  • Necrosis: soft, friable, often cavitates
  • Semiliquid or gelatinous masses: usually tumors, including oligodendroglioma, lymphoma and pituitary adenoma
  • Vascular malformation: vessels larger than usual aggregate of arachnoid vessels, often associated with hemorrhage, may involve meninges or parenchyma
Features to report
  • Specimen type
  • Specimen size (greatest dimension, additional dimensions are optional)
  • Tumor site
  • Tumor size (greatest dimension, additional dimensions are optional)
  • Histologic type
  • Histologic grade (WHO I - IV, other, cannot be determined, not applicable)
  • Margins (involved, uninvolved, cannot be assessed, not applicable)
  • Results of additional studies performed (electron microscopy, cytogenetics, molecular testing, immunohistochemistry)
  • References: Arch Pathol Lab Med 2001;125:1162

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