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47 Cards in this Set

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What are the unique characteristics of tumors in the CNS?
1. Hard to distinguish b/w benign & malignant
2. Hard to resect neoplasms w/o compromising neuro fxn
3. Location! of tumors can be lethal irrespective of histo type'
4. Malignant tumors of CNS seldom spread beyond CNS but are capable of seeding brain & sc.
What are the four major classes of brain tumors?
Gliomas, neuronal tumors, poorly differentiated neoplasms, & meningiomas.
What three tumors are derived from glial cells.
Astrocytomas, oligodendrogliom, ependymomas.
Astocytomas/Glioblastomas: General Characteristics
-80% of primary brain tumors
-Usually involve cerebral hemispheres.
-30-50 y/o
Astrocytoma Morphology
-Glios easy to see b/c of necrosis, hemorrhage.
-Low grade or well differentiated astros-->mild to moderate inc of glial cells, variable nuclear pleomorphism & network of fine GPAP + astorocytic processes, so fibrillary appearance.
-Indistinct transition from nl to neoplastic tissue
-Anaplastic astros more cellular w/ more nuclear polymorphism & mitotic figures.
Whats the difference b/w glioblastomas morphology & apaplastic astros?
Similar histo but 2 add'l features: areas of NECROSIS & vascular or endothelial proliferation. Glios cross midline.
Whats the difference in molecular genetics b/w low and high grade astros?
Low grade: inactivation of p53 & overexpression of PDGF-A & its receptor
Transition of higher grade: add'l disruption of tumor-suppressior genes, the RB gene; the p16/CKNZA gene.
Whats the difference b/w a primary glioblastoma & a secondary glio?
Primary: arose as glioblastoma de novo (rapid, progressive clinical course, older pts, assoc w/ amplification of EGRF gene)
Secondary: aroze from preexisting lower grade astro (shared p53 mutations found in low grade gliomas, 2 pathways to secondary glio: PDGF-A amplification or MCM2 overexpression; p16 deletion of PTEN mutation)
Describe the clinical course of astrocytomas.
-Get more anaplastic w/ time.
-well differentiated: >5 yr mean survival.
-More rapid course correlated w/ development of more anaplastic features & more rapid growth of tumors.
-Poor prognosis for glios w/ 8-10 month mean survival.
What are the characteristics of Pilocytic (Low grade) Astros?
-benign clinical condition.
-in kids, young adults
-usually site: cerebellum (floor of 3rd ventricle, optic nerves, cerebral hemispheres),
Morphology: cystic w/ nodule in wall of cyst (mural nodule)
-Grow very slowly.
What are the general characteristics of oligodendrogliomas?
-15-20% of gliomas.
-Age group: 30-40s
-Site: cerebral hemisphere w/ white matter preference.
Which cells have perinuclear halos?
oligodendroglia
What are the molecular genetics of oligodendrogliomas?
Most common: genetic alterations: loss of heterozygosity for chrom 1p & 19pq.
As tumors get more anaplastic: loss of 9p & 10q, mutation in CDKNZA.
-Tumors w/ loss of 1p & 19q respond better to tx (radiation, chemo)
-W/o loss of 1p & 19z, refractory to tx.
What is the clinical course of oligodendrogliomas?
better than astrocytomas, mean survival of 5-10 yrs.
General characteristics of ependymomas.
Location: ependyma-lined ventricular system, incl spinal cord.
In 1st 2 decades: usually arise near 4th ventricle.
-5-10% of primary brain tumors in aboce age group.
-In adults, spinal cord become the usual site.
Describe the morphology of ependymomas.
-perivascular pseudorosettes (central vessel w/ tumors cells radiating from it);
-close to vital centers in pons & medulla-->so hard to surgically remove.
-Tumors are GFAP positive.
-Most, well differentiated & behave accordingly.
What is the molecular genetics of ependymomas?
B/c they form part of NF type 2-->the NF2 gene on chromosome 22 has been investigated for spinal cord ependymomas only.
Describe the clincal course of Ependymomas.
-Often w/ hydrocephalus due to 4th ventricle obstruction.
-Poor prognosis b/c of tumor location, mean survival 4 years.
Whats the most common poorly differentiated neoplasm?
Medulloblastoma (20% of brain tumors in kids)
Describe the general characteristics of medulloblastomas.
kids, cerebellum exclusively;
neuronal & glial markers may be expressed, but tumor often largely undifferentiated.
Morphology of Medulloblastomas
Extremely cellular w/ sheets of anaplastic cells. Individual tumor cells are small, mitotic figures are abundant; markers of cellular proliferation, like Ki-67, found in high percentage of cells. May find neurosecretory granules & Homer Wright rosettes. Can have dissemination into sc. Can have 'drop mets: may spread to cauda equina thru most direct manner.
What is the clincal course for medulloblastoma.
W/ total excision & radiation, 5 yr survuval rate may be as high as 75%.
-Tumor is exquisitely sensitive to radiation.
General characteristics of meningiomas.
benign tumors of adults;
attached to dura & arise from meningothelial cells of arachnoid;
-low risk of recurrence or aggressive growth.
-aggressive tumors may occur.
-various histo patterns that have no influence on prognosis.
What are the most common locations of meningiomas?
Common involvement areas: parasagittal area, wing of sphenoid, olfactory groove, sella turcica, foramen magnum.
Usually solitary lesions.
-Often carry progesterone receptors, so rapid growth during pregnancy has been reported.
What is the most common tumor in immunosuppressed patients?
Primary CNS lymphoma
Which tumors account for approximately 25-50% of intracranial tumors in hospitalized patients?
Metastatic tumors
What are the top 3 places that metastatic CNS tumors metastasize from?
lung, breast, melanoma
Which tumors almost never metastasize to brain?
prostate CA
What is a common site of involvement for metastatic tumors?
meninges
Describe the morphology of metastatic tumors
Sharply demarcated from brain parenchyma, Site: jxn of gray and white matter. Meningeal carcinomatosis: tumor involves brain surface & spinal cord & intradural nerve roots assoc w/ small CA of lung & CA of brest.
What is the most common clinical cause of neuropathy?
Diabetes.
What is the most common inherited cause of neuropathy?
Charcot-Marie-Tooth Disease
What are some of the principal causes of peripheral neuropathy?
Autoimmunity, vasculitis, systemic illness, CA, infections, dysproteinemia, nutritional deficiencies, alcoholism, compression, trauma, industrial agents, drugs, inherited neuropathies.
What are immune-mediated neuropathies?
Immune disorders, antibodies react w/ antigens on peripheral N, elicit response & macrophage rxn, destroying myelin & axons.
What are the 2 main groups of immune-mediate neuropathies?
Guillan-Barre syndrome, chronic inflammatory demyelinative neuropathy.
What are the clinical findings of Guillain Barre syndrome?
parasthesias, toes, & fingertips. Rapidly advancing weakness & areflexia. Plateau in 4 weeks, recovery begins. Some cases fulminant, evolve in 1-2 days. Follows upper respiratory infection, usually post-viral (Camp Jejuni).
What is the tx for GBS?
Plasma exchange treatment of choice (exchange transfusion)
What is the outcome for GBS?
5% die of respiratory paralysis, cardiac arrest, other complications;
10% recover w/ residual weakness
-Key lab abnormalities: Dec nerve conduction velocity or conduction block.
-CSF: elevated protein, relatively few cells (albuminocytologic dissociation)
Describe Charcot-Marie-Tooth Disease
-Most common inherited peripheral neuropathy,
-Involves 1/2500, AD.
-Wkness, atrophy of distal muscles, specifically those innervated by peroneal nerve ('stork leg')
-begins in childhood or adolescence, progresses slowly, involves other nerves.
-Dec conduction velocity in nerves.
What do you see on a nerve biopsy in Charcot Marie Tooth disease?
demyelination, myelin regeneration (thin myelin), axonal loss, onion bulbs.
Whats the most common form of CMT, type 1?
Dup of chro 17, contains gene for myelin protein, PMP22. CMT-1 pts, 3 copies of normal gene, produce 1.5 x as much PMP22 as normals do.
What are the best tissues for diagnosis of vasculitis?
sural nerve biopsy & muscle biopsy-->nerve biopsy is diagnostic, over 50% of pts w/ systemic vasculitis & clinical neuropathy.(yield inc w/ muscle biopsy too)
What is the development of peripheral nerve sheath tumors?
Arise from Schwann cells, perineural cells & fibroblasts.
-Peripheral nerve: axon w/ Schwann cells plus myelin sheath.
-Schwann cells envelopes, isolates variable numbers of unmyelinated fibers.
Describe the origin and morphology of a Schwannoma (Neurilemmoma)
Origin: Schwann cells, arise from neural crest, assoc w/ NF-type 2.
Morphology: Antoni type A and Type B.
What are the clinical features of a Schwannoma?
acoustic neuroma (8th nerve), deafness, vertigo., trigeminal nerve (trigeminal neuralgia)
What are the 2 types of neurofibromas?
1. Cutaneous form
2. Peripheral nerve (solitary neurofibroma)q
Describe a neurogenous sarcoma.
Highly malignant, frequent recurrences, eventual metastases.
-Frequently mutliple-->from neurofibroma.
-may follow radiation therapy.
-assoc w/ NF type 1.