1. Case Study 2
Harry Kellermier

2. Question 1
The following smear is from an intraoperative consultation for an 81-year-old female who presents with progressive loss of vision in her left eye and a large mass in the temporal region of her scalp. Imaging is not available. Intraoperatively, the surgeon informs you that the tumor involves the dural aspect of the skull as well as the skin surface. Describe the following smear taken during this procedure. Click here to view slide.

3. Answer
a.  Cellular lesion
b.  Pseudosyncytial pattern
c.  Whorl- like structures
d.  Cells show:
     i.  Pulled taffy cytoplasm
    ii.  Intranuclear pseudoinclusions
   iii.  Some show prominent nucleoli
e.  Mitoses are easily found

4. Question 2
What would the intraoperative consultation be based on the previous smear? (A: Category such as Defer, Reactive, or Neoplastic; B: More specific diagnosis, C: additional information)

5. Answer
a.  A: Neoplastic
b.  B: Meningioma
c.  C: A high grade lesion cannot be excluded

6. Question 3
Describe the microscopic findings on the permanent section from the intraoperative specimen. Click here to view slide.

7. Answer
a.  Hypercellular neoplasm composed of atypical cells b.  Pseudosyncytial appearance c.  The tumor invades soft tissue d.  Whorls and Whorl-like areas e.  Vaguely fascicular architecture f.  Areas of sheeting g.  Cells with prominent nucleoli h.  Greater than 20 mitoses per 10 high power fields 

8. Question 4
What is the differential diagnosis based on the H&E slide?

9. Answer Spindle cell carcinoma Anaplastic meningioma Leiomyosarcoma
Melanoma
Atypical fibrous xanthoma/malignant fibrous histiocytoma
Hemangiopericytoma with atypical features
Solitary fibrous tumor with atypical features

10. Question 5
What immunohistochemical stain would you order to narrow your differential diagnosis?

11. Answer EMA (Positive in meningioma)
Ki-67 (Assess proliferative ability of tumor)
S100 (Positive in melanoma)
SMA (Positive in leiomyosarcoma)
CD34 (Positive in solitary fibrous tumor and hemangiopericytoma)
BCL-2 (Positive in solitary fibrous tumor
Cytokeratins (Positive in carcinomas)
Vimentin (Positive in meningiomas and other tumors)

12. Question 6
What is the proliferation index of this tumor? Click here to view slide.

13. Answer
20-30%

14. Question 7
The EMA and vimentin come back positive. What is your diagnosis? Click here to view slide.

15. Answer
Anaplastic meningioma

16. Question 8
What is the characteristic appearance of a meningioma on MRI?

17. Answer
Enhancing
Dural tail

18. Question 9
Name the subtypes of meningiomas

19. Answer
Anaplastic; Rhabdoid; Papillary; Atypical; Chordoid; Clear cell; Meningothelial; Fibrous; Transitional; Microcystic; Psammomatous; Angiomatous (Don't use the term angioblastic meningioma.  That's an old term for a hemangiopericytoma); Metaplastic; Secretory; Lymphoplasmacyte-rich

20. Question 10
What WHO grade are most meningiomas?

21. Answer
WHO grade 1

22. Question 11
What subtypes are considered WHO grade 2?

23. Answer
a. Atypical b. Chordoid c. Clear cell

24. Question 12
What histologic characteristics are needed to make a diagnosis of atypical meningioma?

25. Answer
a.  4 mitoses per 10 hpf b.  3 out of the following 5 criteria:       i.  hypercellularity      ii.  necrosis     iii.  macronucleoli      iv.  small cell change      v.  sheeting

26. Question 13
What subtypes of meningioma are considered to be WHO grade 3?

27. Answer
a. Anaplastic b. Rhabdoid c. Papillary

28. Question 14
What histologic characteristic is needed to make a diagnosis of anaplastic meningioma?

29. Answer
20 mitoses per 10 hpf