Chap 28 Morphology 4 Flashcards
What are the characteristics of diffuse astrocytomas?
Poorly defined, gray infiltrative tumors that expand and invade the brain
What is always present in a diffuse astrocytoma?
Infiltration beyond the outer margins
What is the microscopic appearance of a diffuse astrocytoma?
- Greater cellular density than normal white matter
- Astrocytic processes
- Indistinct transition between neoplastic and normal tissue
What are the characteristics of an anaplastic astrocytoma?
- More densely cellular
- Greater nuclear pleomorphism
- Mitotic figures present
What is a gemistocytic astrocytoma?
A tumor where the predominant neoplastic astrocyte shows brightly eosinophilic cell body
What is the histologic appearance of a glioblastoma?
- Similar to an anaplastic astrocytoma + necrosis and vascular endothelial cell proliferation
What is pseudo-palisading?
A histologic pattern where the tumor cells collect along the edges of the necrotic regions
What occurs with vascular cell proliferation in glioblastomas?
- Tuft of cells pile up and create a double layer of endothelial cells
- Forms a ball-like structure called a glomeruloid bodyt
What is the relevance of VEGF in relation to vascular change in glioblastomas?
VEGF is produced by malignant astrocytes in response to hypoxia
What is gliomatosis cerebri?
A diffuse glioma with extensive infiltration in the brain
*Considered a grade III/IV lesion
What are the common characteristics of pilocytic astrocytomas?
Cystic and usually well circumscribed
What cells are present in a pilocytic astrocytoma?
Bipolar cells with long, thin “hairlike” processes that form fibrillary meshworks
What can be a characteristic finding for a pilocytic astrocytoma?
Rosenthal fibers and eosinophilic granular bodies
What is a difference between diffuse fibrillary astrocytomas and pilocytic astrocytomas?
Pilocytic astrocytomas show limiting infiltration to the surrounding brain whereas diffuse filbrillary astrocytomas do show infiltration
What is the appearance of oligodendrogliomas?
Well circumscribed, gelatinous, gray masses, cystic, focal hemorrhage, minimal mitotic activity and calcification
What is the histology of the cells in an oligodendroglioma?
Cells with spherical nuclei containing finely granular chromatin surrounded by a clear halo of vacuolated cytoplasm
What are the characteristics of an anaplastic oligodendroglioma?
High cell density, nuclear anaplasia, detectable mitotic activity, and necrosis
What cells and cellular components are in ependymomas?
- Cells with regular, round to oval nuclei and abundant granular chromatin
- Dense fibrillary background
- Tumor cells that form rosettes or canals
What are rosettes?
Gland-like round structures formed by tumor cells
*Found in ependymomas
What are canals?
Elongated structures formed by tumor cells that resemble the embryologic ependymal canal
*Found in ependymomas
When are perivascular pseudorosettes present?
When tumor cells are arranged around vessels with an intervening zone of thin ependymal processes directed toward the wall of the vessel
What are the characteristics of an anaplastic ependymoma?
Increased cell density, high mitotic rates, areas of necrosis, and less ependymal differentiation
What are myxopapillary ependymomas?
Lesions that occur in the filum terminale of spinal cord
What are the characteristics of a myxopapillary ependymoma?
- Have cuboidal cells around papillary cores containing connective tissue and blood vessels
- Contain neutral and acidic mucopolysaccharides
What is the difference in location of medulloblastomas in children vs adults?
Children: located in the midline of the cerebellum
Adults: lateral locations of the cerebellum
What is the appearance of a medullablastoma?
- Well circumscribed, gray, and friable
- Mitoses are abundant and markers of cellular proliferation are in high percentage
Microscopic examination of medullablastomas
- Very densely cellular with sheets of anaplastic cells
- Single cells are hyperchromatic nuclei and elongated or crescent shaped
What tumors are Homer-Wright rosettes found?
Medullablastomas and neuroblastomas
What is the nodular desmoplastic variant in medullablastomas?
- Area of stomal response marked by collagen and reticulin deposition
- Nodules forming “pale islands”
What is the large cell variant in medullablastomas?
- Large irregular vesicular nuclei , prominent nucleoli, and frequent mitosis and apoptotic cells
What is the term “drop metastases”?
When nodular masses form at distance from the primary tumor mainly from CSF dissemination
Characteristics of atypical teratoid/rhabdoid tumor
Large, soft consistency, that spread along surface of the brain and have lots of mitotic activity
What is the appearance of a rhabdoid cell?
- Eosinophilic cytoplasm
- Sharp cell borders
- Eccentrically located nuceli
Characteristics of Primary CNS lymphoma lesions
Lesions are multiple and involve the deep gray matter, white matter, and cortex
What is the most common histologic group of primary CNA lymphomas?
B-cell lymphomas
What is the histologic pattern, “hooping”, and when does it occur?
Hooping is when infiltrating cells are separated form one another by silver-staining material
*Seen in primary brain lymphomas
What marker is expressed in Primary CNS lymphomas?
B cell markers- CD20
What is the appearance of a meningioma?
- Rounded mass with well-defined dural bases that compress underlying brain
- Surface is encapsulated by fibrous tissue
What is “en plaque” and when is it seen?
When the tumor spreads in a sheetlike fashion along the surface of the dura
*Seen in meningiomas
What is the histologic pattern, syncytial, and when is it present?
Whorled clusters of cells that sit in tight groups without visible cell membranes
*Seen in meningiomas
What is the histologic pattern, fibroblastic, and when is it present?
Elongated cells with abundant collagen deposition between them
*Seen in meningiomas
What is the histologic pattern, transitional, and when is it present?
Share features of syncytial and fibroblastic
*Seen in meningiomas
What is the histologic pattern, psammomatous, and when is it present?
Psammona bodies that form from calcification of syncytial nests of meningothelial cells
*Seen in meningiomas
What is the histologic pattern, secretory, and when is it present?
PAS-positive intracytoplasmic droplets and intracellular lumens by electron microscopy
*Seen in meningiomas
What is the histologic pattern, microcystic, and when is it present?
Loose, spongy appearance and is associated with a specific genotype–> mutations in TRAF7 and KLF4
*Seen in meningiomas
What is an atypical meningioma?
A lesion with a higher rate of recurrence and more aggressive local growth
How are atypical meningiomas distinguished?
Have 4 or more mitoses per 10 power fields or at least 3 atypical features
What are examples of atypical features?
Increased cellularity, small cells with high nuclear-to-cytoplasmic ratio, prominent nucleoli, patternless growth, or necrosis
What is an anaplastic (malignant) meningioma?
Highly aggressive tumor with the appearance of a high-grade sarcoma but retain histologic evidence of meningioma origin
Papillary Meningioma
Pleomorphic cells arranged around fibrovascular cores
Rhabdoid Meningioma
Sheet of tumor cells with hyaline eosinophilic cytoplasm containing intermediate filaments
Characteristics of intraparenchymal metastases
- Sharply demarcated
- At the junction of gray and white matter
- Surrounded by a zone of edema
What metastatic tumor is associated with carcinoma of the lung and breast?
Meningeal carinomatosis
Characteristics of cortical hamartomas of tuberous sclerosis
Firm areas of cortex that are comprised of haphazardly arranged neurons that lack organization
What does “candle-guttering” mean and when is it seen?
- Droplike masses that bulge into the ventricular system
* Seen in tuberous sclerosis
What are hemangioblastomas?
Highly vascular neoplasms that occur as a nodule and are associated with a large fluid-filled cyst
What is considered the neoplastic element in hemangioblastomas and why?
Stromal cells that express inhibin- they are the neoplastic element because they show the presence of the second “hit” in the preciously normal VHL allele
