Neuro

Question 1

Describe the main histologic features of the different grades of meningiomas

Answer 1

Grade I
meningothelial (conventional, syncitial) - lobules (whorls) separated by fibrous bands of bland cells with abundant cytoplasm, cleared out nuclei, and pseudoinclusions. In the lobules the cells are syncitial (dont; confuse with sheeting)

fibrous - rare in pure form, just fibroblast like spindle cells with lots of collagen, few psammomas and little whorling (can look like SFT - use EMA and CD34)

mixed - common, mixture of above two.

psammomatous - mostly psammomas, lots of calc, and some ossification

angiomatous - mostly thick and thin walled vessels

Microcystic - little microcysts with pale, eosinophilic mucinous material

secretory - pseudopsammomas (PAS+) in intracellular lumina. can have lots of vessels also

lymphoplasmacytic - rare, controversial, mostly chronic inflammation, behaves like inflammatory process, often concommittant systemic hematologic problem

metaplastic - has abundance of mesenchymal (osseous, chondroid, lipomatous, myxoid) or xanthomatous elements

Grade II
chordoid - mostly resembles chordoma (cords of epithelioid cells in a myxoid stroma)

clear cell - sheets of clear cells, little whorling, no psammomas

atypical (any other type can be atypical if it meets criteria)
either 1) >4 mit/10 HPF
OR
2) 3 of the following a) “sheeting” growth, b) hypercellularity, c) increased N:C ratio, d) tumor cell necrosis (don’t confuse with embolization infarct necrosis or e)prominent nucleoli

Grade III
papillary - perivascular, pseudopapillary growth

rhabdoid - sheets of rhaboid cells and other features of malignancy

anaplastic - frankly malignant

Question 2

what growth feature affect grading of meningiomas (and what don’t)

Answer 2

Brain invasion (irregular tongues w/o intervening leptomeninges, not just compression) - most brain-invasive meningiomas are histologically grade I, but they have an increased risk of recurrence and should be considered grade II

Skull and dural invasion are NOT considered in grading (but there is still likelihood of recurrence with these features) - these are usually grade I

Question 3

What meningiomas are more likely to be associated with cerebral edema?

Answer 3

secretory (main one)
angiomatous
microcystic
also any grade II or grade III tumors

Question 4

Main gene mutated in menigiomas? And the chromosome?

Answer 4

NF2 (chromosome 22)

Question 5

What are the IHC characteristics of meningiomas, including special types?

Answer 5

EMA + (but lost in atypical and higher grade forms)

PR variable, often +
ER -
S100 variable

CK variable, except for secretory type in which pseudopsammomas and the cells containing them are CK7, 8, 18, and AE1 / AE3 +)

CEA - highlights secretory pseudopsammomas and the cells containing them