1. Case Study 37
Henry Armah, M.D., M.Phil.

2. Question 1
Clinical history: 75-year-old female with history of back pain and bilateral lower extremity weakness. He was a non-smoker, occasionally used alcohol socially, and did not use illicit drugs. Spinal MRI revealed a large (6.0 cm in largest dimension) extra-axial intradural mass at the level of T10-11 vertebrae. The mass was completely resected at an outside hospital and the permanent section sent to you for consultation. Describe the microscopic findings on this H&E slide? Click here to view slide.

3. Answer
Fragments of a malignant pleomorphic tumor with both spindle and epithelioid components. The epithelioid component appears to focally form gland-like structures. Mitotic figures are readily identified.

4. Question 2
What are your differential diagnoses based on the patients’ age and histological findings?

5. Answer
Malignant Peripheral Nerve Sheath Tumor
High-grade Glioma

6. Question 3
What additional studies would you need to rule out other important differential diagnoses and confirm the final diagnosis in this case?

7. Answer
GFAP, S-100, Neurofilament, and Ki-67 (MIB-1).

8. Question 4
What do you see on this S-100 immunostain slide? Click here to view slide.

9. Answer
S-100 is moderately positive in scattered spindled and epithelioid tumor cells.

10. Question 5
What do you see on this GFAP immunostain slide? Click here to view slide.

11. Answer
GFAP is negative in tumor cells.

12. Question 6
What do you see on this Neurofilament immunostain slide? Click here to view slide.

13. Answer
Neurofilament is weakly positive in rare tumor cells.

14. Question 7
What do you see on this Ki-67 (MIB-1) immunostain slide? Click here to view slide.

15. Answer
Ki-67 (MIB-1) is positive in the nuclei of up to 25% of tumor cells.

16. Question 8
What is your final diagnosis in this case?

17. Answer
Malignant Peripheral Nerve Sheath Tumor

18. Question 9
Which of the following familial tumor syndrome is this lesion commonly associated with?
Turcot syndrome
Neurofibromatosis type 1
Neurofibromatosis type 2
Von Hippel-Lindau disease
Li-Fraumeni syndrome

19. Answer
B. Neurofibromatosis type 1