Case Study 44 Julia Kofler, M.D.

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.

Question 1 T1 T1 with contrast T1 with contrast

Answer Diffusely contrast-enhancing suprasellar mass

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

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

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.

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

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

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

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

Answer PAS w/wo diastase S100 GFAP

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).

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

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

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

Question 8 What is your final diagnosis in this case?

Answer Granular cell tumor

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

Answer Pituicytes

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

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