Meningioma

Histopathology

Secretory meningiomas have gland-like lumina, often containing PAS-positive hyaline globules ("pseudopsammoma bodies"). The lumina are surrounded by one or more layers of thin epithelium-like cells which are positive for a range of cytokeratins and for EMA and CEA4. There may be a pericytic proliferation within vessel walls4.
Meningothelial meningiomas are composed of sheets of cells with abundant, variably eosinophilic, cytoplasm.
Transitional meningiomas have an appearance intermediate between those of meningothelial and fibroblastic meningiomas.
Fibroblastic meningiomas show curving fascicles of spindle cells with abundant collagen. Sparse psammoma bodies are commonly present.
Psammomatous meningiomas contain abundant psammoma bodies, often within a spindle cell meningioma.
Microcystic meningiomas have a porous microcystic pattern with prominent vasculature.
Choroid meningiomas have trabeculae of cells within a myxoid stroma.
Anaplastic meningiomas ware defined as those containing >20 mitoses per 10 HPF or having cytologic features resembling carcinoma or melanoma

Immunohistochemistry

Epithelial markers:

Meningioma subtype

CK16

CK17

Secretory

19/20(positivity in gland-like elements)1, 9/92

20/20(positivity in gland-like elements)1

9/92

0/92

Meningothelial

1/601

16/601

3/601

6/601

1/601

43/601

33/601

5/60(only trace positivity)1

Transitional

0/2001

44/2001

18/2001

25/2001

0/2001

138/200(staining >10% of cells in 80 cases)1

80/2001

17/2001

Fibroblastic

0/1001

14/1001

5/1001

0/1001

54/1001

28/1001

5/1001

Psammomatous

0/101

4/101

1/101

4/101

0/101

7/101

8/101

1/101

Microcystic

0/71

2/71

1/71

0/71

7/7(positivity is often extensive)1

2/71

0/71

Choroid

0/21

1/2(few cells)1

0/21

1/2(2% of cells)1

1/2(few cells)1

0/21

Atypical

0/601

26/601

22/601

19/601

0/601

52/601

30/601

12/601

Anaplastic

0/41

3/41

2/41

0/41

0/41q

4/4(positivity in 20% to 100% of cells)1

2/41

NOS

100%3

Other cytokeratins: CK10 and CK15 were negative in all 4631 meningiomas studied. CK20 was negative in all 4711,2 meningiomas studied. Extremely limited focal expression of CK13 was seen in one secretory meningioma around luminal structures and in one transitional meningioma at the periphery of whorls1.

In summary:

CK18 is the most commonly expressed cytokeratin. This parallels the positivity in normal arachnoid1.
CK8 is expressed by secretory, atypical and anaplastic meningiomas

Other marker:

	S-100	39%3
	vimentin	100%3

Prognosis

The risk of recurrence and aggressive behaviour depends on location, brain invasion, histological subtype and mitotic index. The WHO grading recognises:

benign (grade I)
atypical (grade II
anaplastic (grade III)

Anti-PHH3 is reportedly useful in assessing the mitotic index and the malignancy of meningiomas.

Differential diagnosis

metastatic carcinoma: carcinomas and meningiomas are both positive for EMA. The importance of the various specific cytokeratins depends on the site of the putative primary adenocarcinoma.

References

1Miettinen, M. and Paetau, A. Mapping of the keratin polypeptides in meningiomas of different types: an immunohistochemical analysis of 463 cases. Hum Pathol 2002;33:590-8.

2Assi A., Declich P., Iacobellis M., Cozzi L., Tonnarelli G. Secretory meningioma, a rare meningioma subtype with characteristic glandular differentiation: an histological and immunohistochemical study of 9 cases. Adv Clin Path 1999; 3:47-53.

3Radley, M. G., P. A. di Sant'Agnese, et al. (1989). "Epithelial differentiation in meningiomas. An immunohistochemical, histochemical, and ultrastructural study--with review of the literature." Am J Clin Pathol 92(3): 266-72.

4Alguacil-Garcia, A., N. M. Pettigrew, et al. (1986). "Secretory meningioma. A distinct subtype of meningioma." Am J Surg Pathol 10(2): 102-11.

This page last revised 24.12.2003.