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Nervous System: Unit IV > Neoplasms > Flashcards

Flashcards in Neoplasms Deck (12)
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WHO Grade I lesions characteristics

  • tumors with low proliferative potential and high possibility of cure following surgical resection alone
  • Well demarcated, surgically excisable.

3

WHO Grade I lesion example

  • Example: pilocytic astrocytoma               
  • occurs @ childhood
  • @ cerebellar hemispheres, optic nerves and chiasm, and hypothalamic region.           
  • Gross total resection possible @ cerebellar lesion
  • gross total resection impossible @ optic chiasm or hypothalamus

4

WHO Grade II lesion characteristics

  • generally infiltrative  
  • low level proliferative (ie., mitotic) activity,
  • often recur.
  • Some grade II tumors tend to progress to a higher grade of malignancy

5

WHO Grade II lesion example

  • Example: diffuse astrocytoma.  
    • Hits adults age 30-50, has ill-defined borders, not surgically resectable
  • Progression examples: low-grade diffuse astrocytomas (WHO grade II) ==> anaplastic astrocytoma (WHO grade III) or glioblastoma (WHO grade IV) over a few years time.
    • Similar transformation to higher grade tumor occurs also in oligodendrogliomas and mixed (oligoastrocytomas) gliomas. 

6

WHO Grade II treatment

  • watchful waiting (ie., close-interval neuroimaging scans to detect upgrading)

  • external beam cranial irradiation, depending on location, clinical features, type and size of lesion.

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WHO Grade III lesion characteristics & example

  • lesions with histological evidence of malignancy, including nuclear atypia and brisk mitotic activity.
  • patients with Grade III tumors receive adjuvant radiation and/or chemotherapy.
  • Example: anaplastic astrocytoma: more nuclear atypia

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WHO Grade IV lesion characteristics 

  • cytologically malignant, mitotically active, necrosis-prone neoplasms
  • often associated with rapid pre and post operative disease evolution and fatal outcome.
  • Common examples of Grade IV neoplasms include glioblastoma and medulloblastoma.

9

Glioblastoma characteristics

  • WHO Grade IV lesion
  • Highly infiltrative, often hemorrhagic neoplasm that is necrotic at the microscopic and sometimes gross level.

  • Dismal prognosis.  More than 90% of GBMs are primary, only 2-4 months of symptoms.
  • Has a bright rim and necrotic center on CT scan.  
  • Necrotic center releases HIF and VEGF which causes blood vessels to start developing again and vascularizes the rest of the tumor. 
  • Secondary GBM: progression from lower grade tumor, younger age (

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General treatment approaches for WHO grade I - IV tumors

1: cut it out and it’s ok

2: can’t resect, will often upgrade to grade 3 or 4.  Treat with radiation and close observation

3: chemo + radiation

4: rapid growth, fatal, adjuvant therapy has little data supporting use

Tempo parallels grade: Grade 1 grows slowly, grade 4 grows quickly

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Histologic typing/grading and prognosis

  • Grading: look at the tumor in microscope and decide how aggressive it will behave (mitotic figures, vascularity and necrosis, invasion).
  • Tells you how you will have to treat it and how fast it will kill.

12

Tumor types that tend to spread throughout CSF axis

  • Astrocytomas and oligodendrogliomas DO NOT ==> into the CSF pathway and disseminate through the cerebrospinal fluid.
  • DOES occur late in the course of some ependymomas, especially those in childhood and originating in the 4th ventricle, and especially in medulloblastomas.