1. Case Study 44
Julia Kofler, M.D.

2. Question 1
Clinical history: 36 year old female with a 5 year history of panhypopituitarism and increasing visual deficits. Describe the lesion on the following MRI scan.

3. Question 1
T1 T1 with contrast T1 with contrast

4. Answer
Diffusely contrast-enhancing suprasellar mass

5. Question 2
What is your differential diagnosis based on the radiologic appearance and location of the lesion?

6. Answer Pituitary adenoma Craniopharyngioma Pituicytoma
Granular cell tumor
Meningioma
Pilocytic astrocytoma
Germ cell tumor

7. Question 3
An endoscopic endonasal resection was performed. An intraoperative consultation was requested. What is your interpretation of the following touch prep? According to the surgeon, the mass appears to be arising from the infundibulum. Click here to view slide.

8. Answer Hypocellular touch prep consisting predominantly of blood
No evidence of pituitary adenoma
Rare large polygonal cells with abundant granular cytoplasm (macrophages vs granular cells)
Overall, a granular cell tumor is favored

9. Question 4
Describe the findings on the permanent section. Click here to view slide.

10. Answer
Moderately cellular neoplasm composed of elongated to large polygonal cells with abundant coarsely granular cytoplasm and eccentric nuclei with inconspicuous nucleoli.

11. Question 5
Which stains may be ordered to further work up this case?

12. Answer
PAS w/wo diastase
S100
GFAP

13. Question 6
What is your interpretation of the following stains? Click here to view PAS-D slide. Click here to view S100 slide (red chromogen). Click here to view GFAP slide (brown chromogen).

14. Answer PAS-D strongly stains the cytoplasmic granules
S100 is patchy weakly to moderately positive
GFAP is negative in the tumor cells; highlights rare glial processes at the edge of the tumor

15. Question 7
Is this the expected staining pattern for infundibular granular cell tumors?

16. Answer
Yes
PAS and PAS-D strongly stain the cytoplasmic lysosomal granules
S100 is usually positive, but may be variable
GFAP is usually negative

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

18. Answer
Granular cell tumor

19. Question 9
What is the presumed cell of origin of granular cell tumors?

20. Answer
Pituicytes

21. Question 10
Name a lesion that is related to infundibular granular cell tumors and can be seen incidentally in ~10% of autopsy pituitaries?

22. Answer
Granular cell tumorlet/tumorette/choristoma is a microscopic granular cell proliferation in the infundibulum or neurohypophysis and histologically similar to the larger granular cell tumor