Transcript Case Study - University of Pittsburgh

Case Study 52
Edward D. Plowey
Case History
 The patient is a 48 year old woman with a 3-year
history of migraine headaches and recent development
of a subtle right visual field loss.
 The patient underwent an MRI of the brain to further
investigate a potential cause of these symptoms.
Question 1
Describe the radiologic abnormality in the following MRI
images.
T2 FLAIR
T1
T1 POST-CONTRAST
Answer
T1 weighted images show an extra-axial parafalcine mass lesion
impinging on regions of the left parietal and occipital lobes. The
tumor exerts mass effect that distorts the left lateral ventricle and
induces considerable parenchymal vasogenic edema. The tumor
shows avid contrast enhancement and appears to show a dural tail on
the post-contrast T1-image.
Question 2
What is the differential diagnosis for this lesion?
Answer
The differential diagnosis of this lesion includes:
Meningioma
Hemangiopericytoma
Solitary Fibrous Tumor
Alternative dural-based mesenchymal neoplasm
Metastasis
Question 3: Intraoperative Consultation
 The patient was taken for tumor
resection. An intraoperative
consultation was requested to
confirm the clinical impression of
meningioma.
 A smear preparation yielded tightly
cohesive fragments of fibrous tissue
with moderate cellularity (see image
to right). A frozen section was
subsequently prepared.
 Describe the findings in the virtual
frozen section and render a frozen
section diagnosis.
Answer
 A frozen section demonstrates a moderately cellular neoplasm.
The tumor cells show oblong to spindle nuclei with speckled
chromatin and a loose interlacing fascicular growth pattern focally.
The tumor lacks a lobular growth pattern. An area of microcystic
degeneration versus ice crystal artefact is seen. A hypocellular
area with prominent broad bundles of collagen is seen. No
intranuclear pseudo-inclusions or meningothelial whorls are seen.
Mitotic figures and necrosis are not seen in the frozen section.
 Intraoperative diagnosis:
A. Neoplastic
B. Low grade spindle cell neoplasm
Question 4: Permanent Sections
Examine the following virtual permanent section slides
and delineate a panel of special stains:
Permanent of Frozen Section Tissue
Additional Permanent Section
Answer
 Histologic sections resemble the frozen section and raise the
following differential diagnosis:
 Meningioma (deplete of whorls)
 Hemangiopericytoma / Solitary Fibrous Tumor
 Question 5:
 What panel of immunostains will you order to differentiate among
these entities?
Answer
 Histologic sections resemble the frozen section and raise the
following differential diagnosis:
 Meningioma (deplete of whorls)
 EMA (click to view the virtual slide)
 Hemangiopericytoma / Solitary Fibrous Tumor




CD34 (click to view the virtual slide)
bcl-2 (click to view the virtual slide)
Reticulin (click to view the virtual slide)
Ki67 (click to view the virtual slide)
Question 6
What information do the special stains convey?
What is the final diagnosis?
Answer
 The EMA immunostain is entirely negative, which
argues against the diagnosis of meningioma.
 The tumor shows moderate to strong and diffuse
staining for CD34 and Bcl-2. A Ki67 immunostain
shows a low proliferative index (3-4%).
 A reticulin stain shows that in many areas, the tumor is
lacking in single-cell pericellular reticulin deposition.
 Diagnosis: SOLITARY FIBROUS TUMOR.
Discussion
Compared to meningioma, solitary fibrous tumor (SFT) is a relatively
rare neoplasm, but it should always be considered in the differential
diagnosis of a contrast-enhancing dural-based mass.
The key diagnostic features of SFT are a ovoid to spindle cells
neoplasm with a “patternless” growth pattern and usually prominent
collagen deposition. In contrast to meningioma, which is
immunoreactive for EMA, SFT is usually positive for CD34 and Bcl-2.
CD34 immunoreactivity in SFT has been proposed to be related to
origin from dural fibroblasts. CD34 immunoreactivity in some
meningiomas may be related to fibroblast inclusion in the neoplasm.
Cummings et al. Acta Neuropathol. 102:349-354, 2001.
Discussion
SFT and hemangiopericytoma (HPC) demonstrate several overlapping
histomorphologic features. Some experts favor lumping the two into a
single diagnostic category HPC-SFT in which the two entities represent
ends of a morphologic spectrum of a single entity, especially when
dealing with non-central nervous system tumors.
Evidence supports a vital distinction between SFT and HPC in the
central nervous system (Tihan et al. Arch Pathol Lab Med. 127:432-9,
2003). CNS SFT is an indolent tumor that only occasionally recurs
following resection. CNS HPC usually recurs and often metastasizes
outside the central nervous system to evoke considerable morbidity
and even mortality.
Discussion
HPC often shows more denselypacked, chaotically arranged cells
and fewer areas of broad collagen
bundle deposition. A key
distinguishing feature is the rich
reticulin network surrounding
single tumor cells in HPC (see
example image to the right) that is
not seen in SFT.
Reticulin staining pattern in a case of
dural hemangiopericytoma.