Neuro-Oncology Quiz: Astrocytoma Grading

CNS Tumors - General Information

• Emad Raddaoui, MD, FCAP, FASC, is the professor and consultant.
• Pathology and Cytopathology are the fields of study.
• The presenter seems like a cool guy.

CNS Tumors Incidence

• Annual incidence of intracranial tumors: 10-17 per 100,000 persons.
• Annual incidence of intraspinal tumors: 1-2 per 100,000 persons.
• CNS tumors compromise 10% of all tumors.
• Childhood CNS tumors: second most common type of cancer.
• Common childhood CNS tumors arise in the posterior fossa.
• A comparable number of adult CNS tumors arise in the cerebral hemispheres above the tentorium
• Peak incidence for CNS tumors in adults is in the 50s.
• Incidence of intracranial tumors is higher than intraspinal tumors

CNS Tumors - General Characteristics

• No detectable premalignant or in situ stages comparable to carcinomas.
• Different tumors appear in different age groups.
• Tumors are typically located in specific areas of the CNS causing effects regardless of histological classification.
• Spread patterns of primary CNS neoplasms differ from other tumors in that they rarely metastasize outside the CNS.
• The subarachnoid space is a pathway for spread.
• Recurrent tumors tend to be higher grade.

CNS Tumor Manifestations

• Manifestations are due to tumor size, location, invasiveness, and secondary effects.
• Common symptoms include seizures, headaches and focal neurological deficits.
• Radiological terms "intra-axial" and "extra-axial" refer to tumor location relative to the brain/spinal cord tissue. Intra-axial is in the CNS; extra-axial is outside the CNS.

CNS Tumor Classification

• Tumor types are complicated to classify, and rely on molecular findings.
• Molecular findings are crucial for proper classification.
• Important tumor types highlighted in the slides include, gliomas, CNS cranial and spinal nerves, meningial, mesenchymal, cerebral lymphomas, germ cell tumors, pituitary gland tumors, and metastatic tumors.
• Astrocytes, oligodendrocytes, ependymal, and neuronal cells are highlighted in the classification.
• Glial cells are crucial in the development of the CNS.
  • Tumors originating from these cells (gliomas) are common and have variable grades depending on molecular findings such as IDH (isocitrate dehydrogenase) mutations and 1p/19q co-deletions.

CNS Tumor Diagnostic Procedures

• CT scan, MRI, and PET scan are important imaging techniques.
• CSF (cerebrospinal fluid) analysis is used for diagnosis.
• Biopsy is important to diagnose tumors.
• Histological examination of tissue samples is the gold standard for tumor diagnosis.
• Molecular findings are critical for proper grading and treatment planning.

Histological Patterns: Definitions

• Wholes: concentric onion-like layers of tumor cells.
• Psammoma bodies: laminated calcium deposits within the tumor.
• Palisade: lining up of tumor cells around cytoplasmic processes (no necrosis).
• Pseudopalisading: tumor cells lining up around a central necrotic area.
• Rosettes: tumor cells arranged in a circular pattern around a central lumen.
• Pseudorosettes: tumor cells arranged around blood vessels.
  • The presenter skips several definitions to focus on rosettes.

Histological Variants of Meningioma

• Pictures are shown, highlighting different morphological aspects.
• Psammoma bodies are the concentric areas of calcium deposition.

Metastatic Tumors

• Metastatic tumors are common in adults, originating from lung, breast, skin, kidneys, and gastrointestinal tract (GI) tumors.
• They often occur in the cerebrum (often in gray/white matter junction)
• These tumors are generally discrete and often multiple in location; they also often have some brain edema.
• When they are isolated, this makes it possible that they are primary cancer not metastasis.

Atypical Teratoid/ Rhabdoid Tumor

• Primitive neoplasm, mainly seen in children and has several origins.
• Highly aggressive with poor prognosis and presents with a lack of differentiated cell types, and highly cellular.
• Alterations in chromosome 22 are common, and the tumor is characterized by areas of necrosis and endothelial proliferation.

Primary CNS Lymphoma

• This type of lymphoma frequently occurs in immunosuppressed individuals.
• It originates in the central nervous system (CNS) and can be secondary to lymphoma that spread from parts of the body outside the CNS.
• The tumors are often large B-cell lymphomas.
• Diffuse large B cell histology is characteristic.

Germ Cell Tumors

• Primary germ cell tumors often form along the midline in regions like the pineal and suprasellar areas.
• Most common type of germ cell tumor is germinoma.
• Commonly seen in young patients, with 90% appearing within the first two decades of life.
• Clinically they may look similar to testicular seminoma.

Meningioma

• One of the common primary brain tumors
• Originates from meningothelial cells in the arachnoid
• Often found in adults (ages 60-70s)(6th-7th)

Ependymoma

• Arise from ependymal cells in the ventricular system.
• Common in children (10% of all pediatric intracranial tumors).
• Less common in adults (5% of all adult intracranial tumors).
• Most common location in adults is the spinal cord.
• All glial tumors are GFAP positive.

Oligodendroglioma

• Originates from oligodendrocytes in the white matter.
• Commonly seen in 4th & 5th decades.
• Usually presents as a highly infiltrative grade 2 tumor.
• 1p19q co-deletion is common
• Typically presents with a halo around the tumor, uniform cells, and calcification.

Diffuse Astrocytoma Grade 2

• Poorly defined, gray, infiltrative tumors that expand and distort the invaded brain.
• Size varies from a few centimeters to large lesions.
• It is typically in the anterior cerebral hemisphere

Diffuse Astrocytoma Grade 3 and 4

• These are high-grade tumors and are likely to have a rapid progression
• In grade 3, there should be no necrosis or endothelial proliferation
• Grade 4 shows pleomorphism, necrosis, and highly proliferative microvascular.

Pleomorphic Xanthoglioma

• Most commonly occurs in the temporal lobe of children, usually low-grade.
• Presents with seizures but rarely progresses further.

Medulloblastoma

• High-grade tumor that occurs in the cerebellum.
• Affects children.
• Poor prognosis in untreated patients.
• High mitotic activity, necrosis, and endothelial proliferation.
• Characterized by sheets of small, round anaplastic cells.

Atypical Teratoid/Rhabdoid Tumor (AT/RT)

• A primitive, high-grade tumor that frequently appears in children.
• Characterized by multiple cell lineages and a poor prognosis.
• Contains various types of cells such as epithelial, mesenchymal, and neuroglial cells
• Alterations in chromosome 22 and loss of INI1 protein in nuclei are common.

Test your knowledge on the characteristics and classifications of astrocytomas and other CNS tumors. This quiz covers key differentiating features of various grades, histological appearances, and clinical implications associated with brain tumors. Perfect for students and professionals in neuro-oncology.