Case Study 45Julia Kofler, M.D.

Clinical history:

41 year old male with a 2 year history of progressive hypopituitarism, headache and bitemporal hemianopsia.

Describe the lesion on the following CT scan (no MRI images available due to pacemaker).

Question 1

CT with contrast

Question 1

Diffusely contrast-enhancing suprasellar mass

Answer

Question 2What 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 frozen section and smear preparation?

According to the surgeon, the mass extended around the pituitary stalk and appeared highly vascular

Click here to view frozen section slide.Click here to view smear preparation.

AnswerLow-grade spindle cell tumor

A pituicytoma was favored over other spindle cell neoplasms

Question 4

Describe the findings on the permanent section.

Click here to view slide.

Answer Moderately cellular neoplasm

Comprised of mildly pleomorphic spindle cells with variably distinct cell borders, irregular vesicular nuclei and light eosinophilic cytoplasm with a fibrillar quality

Cells are arranged in groups and haphazardly interwoven fascicles

The fascicles are separated by very thin, compressed vascular channels

No mitoses are seen

No Rosenthal fibers, eosinophilic granular bodies, Herring bodies or oncocytic change is seen

Question 5

What is your differential diagnosis and which stains may be useful to support your diagnosis?

Answer

Pituicytoma, normal infundibulum, pilocytic astrocytoma, spindle cell oncocytoma, granular cell tumor

PAS, S100, GFAP, Neurofilament, EMA, Synaptophysin

Question 6

What is your interpretation of the following stains?

Click here to view PAS slideClick here to view S100 slideClick here to view GFAP slideClick here to view neurofilament slide

AnswerPAS is negative in tumor cells

S100 shows strong nuclear and cytoplasmic reactivity

GFAP is negative in the tumor cells (may be variably positive in pituicytomas)

Neurofilament highlights rare infundibular axons at the margin of the specimen

The tumor was also positive for vimentin and negative for synaptophysin and EMA

Question 7

Name a few features that distinguish pituicytoma from normal infundibulum.

Answer

Normal infundibular tissue is usually less cellular than a pituicytoma (but cellularity may overlap)

Normal tissue is looser in texture and contains axons and perivascular fibrillar zones

Normal tissue contains Herring bodies (PAS positive focal axonal swellings)

Normal tissue is diffusely positive for synaptophysin and neurofilament; pituicytomas are negative

Question 8Name a few features that distinguish pituicytoma from pilocytic astrocytoma.

Answer

Pilocytic astrocytomas commonly occur in children, whereas pituicytomas are usually seen

in adults

Pituicytomas lack Rosenthal fibers and eosinophilic granular bodies that are commonly

seen in pilocytic astrocytomas

Pilocytic astrocytomas usually exhibit a biphasic growth pattern and more variability (compact, piloid, microcystic patterns)

Question 9

Name a few features that distinguish pituicytoma from spindle cell oncocytoma.

Answer

Spindle cell oncocytomas are composed of interlacing fascicles of spindled to

epithelioid cells with eosinophilic to oncocytic cytoplasm

Ultrastructurally, numerous mitochondria are seen

Spindle cell oncocytomas are usually positive for vimentin, EMA, S100 and galectin-3

They are negative for pituitary hormones, GFAP and synaptophysin

Question 10

What is your final diagnosis?

AnswerPituicytoma

Question 11

Name a transcription factor that has recently been shown to be expressed in human fetal and adult pituicytes as well as in a variety of sellar masses (pituicytoma, granular cell tumor, spindle cell oncocytoma)?

AnswerThyroid transcription factor 1, which was also positive in our pituicytoma (see image below)

Reference: Lee EB et al. J Neuropath Exp Neurol 2009;68:482