Case Study 45
Julia Kofler, M.D.
Question 1
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
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 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.
Answer
 Low-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 slide
Click here to view S100 slide
Click here to view GFAP slide
Click here to view neurofilament slide
Answer
 PAS 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 8
Name 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?
Answer
Pituicytoma
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)?
Answer
Thyroid 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