crush preparations of meningiomas: can grading be accomplished?
TRANSCRIPT
DIAGNOSTIC DILEMMASSection Editor: Claire W. Michael, M.D.
Crush Preparations ofMeningiomas:Can Grading Be Accomplished?Sarfraz Ali, M.D.,1 Aziza Nassar, M.D., F.I.A.C.,2
and Momin T. Siddiqui, M.D., F.I.A.C.3*
Crush preparations (CP) for the diagnosis of meningioma areroutinely performed in the frozen section suite when tissue is sub-mitted for intraoperative consultation. The goal of this study wasto examine the cytologic features of meningiomas in CP and eval-uate if benign meningioma (Grade 1), atypical meningioma(Grade 2), and malignant meningioma (Grade 3) can be diag-nosed on CP. All cases of meningioma (1999–2007), which weresubmitted for frozen section at our institution, were retrospec-tively reviewed. These cases were examined intraoperatively byfrozen section and CP. The final histologic diagnosis was takenas the gold standard. A total of 107 meningiomas cases werereviewed. The cytological features of all these cases were studied,and features such as pleomorphism, hemorrhage, necrosis, mito-sis, and presence or absence of nucleoli were recorded. Using thefinal histopathologic diagnosis as the gold standard, there were72 (Grade 1), 22 (Grade 2), and 13 (Grade 3) meningioma cases,which were studied. In conclusion, this study reviews the salientcytologic features of Grades 1–3 meningiomas. It demonstratesthat it is difficult to separate Grade 1 from Grade-2 meningiomaon CP, and last, Grade-3 meningioma can be easily diagnosed onCP. Diagn. Cytopathol. 2008;36:827–831. ' 2008 Wiley-Liss, Inc.
Key Words: meningioma grading; crush preparation cytology
Meningiomas arise from the cells of the arachnoidal lining
or meningothelial cells. These are commonly found in
association with arachnoid villi at the dural venous sinuses
and veins.1,2 Meningiomas account for 30% of all primary
brain tumor diagnoses in adults in the United States.3
These lesions can occur in people of any age but com-
monly present in middle age. Women are more likely to
develop a meningioma, with a female/male ratio of *2:1
intracranially and 10:1 in the spine.4 Ninety percent of all
meningiomas occur in the supratentorial compartment.5,6
Histologically and cytologically, meningiomas represent
a strikingly heterogeneous group of neoplasms. They have
been subdivided into a variety of types, including meningo-
theliomatous, fibrous, transitional, psammomatous, and
angiomatous, among others. About 85% of meningiomas
are benign (Grade I), whereas 10% are atypical (Grade II)
and 3–5% are malignant (anaplastic, Grade III).7 Crush
preparation (CP) for the diagnosis of meningioma are rou-
tinely performed in the frozen section suite when small tis-
sue samples are submitted for intraoperative consultation.
The goal of this study was to examine the cytologic features
of meningiomas in CP and evaluate if benign, atypical, and
malignant meningioma can be diagnosed on CP, alone.
Materials and Methods
All cases of meningioma from 1999 to 2007, an 8-year
period, were submitted for frozen section at our institution
were retrospectively reviewed. A total of 107 meningioma
cases were reviewed in our study. All cases were exam-
ined intraoperatively by frozen section and CP. The tumor
samples were obtained by either using biopsy forceps or
surgical resection. These samples were placed in normal
saline and submitted to the frozen section laboratory for a
diagnosis. Approximately 1–2-mm diameter tissue frag-
ment from each specimen was gently crushed between
two glass slides. The smears were then prepared by using
both, 95% ethanol-fixed slides, which were stained with
hematoxylin and eosin, as well as air drying and staining
by Diff-Quik technique.
1Department of Pathology and Laboratory Medicine, Emory UniversityHospital, Atlanta, Georgia
2Department of Pathology, Mayo Clinic, Rochester, Minnesota3Department of Pathology and Laboratory Medicine, Emory University
Hospital, Atlanta, Georgia*Correspondence to: Momin T. Siddiqui, M.D., F.I.A.C., Emory Uni-
versity Hospital, Department of Pathology and Laboratory Medicine,1364 Clifton Road, NE, Atlanta, GA 30322. E-mail: [email protected]
Received 21 May 2008; Accepted 20 June 2008DOI 10.1002/dc.20929Published online in Wiley InterScience (www.interscience.wiley.com).
' 2008 WILEY-LISS, INC. Diagnostic Cytopathology, Vol 36, No 11 827
Results
A total of 107 meningioma cases were studied. The loca-
tions of these tumors varied and are summarized in Table I.
The final diagnosis of these cases showed that 72 cases
were of Grade I, 22 were of Grade II, and 13 cases were
of Grade III. Mitotic activity on the CP was specifically
studied in detail and given a score ranging from 0 to 2 (0,
no mitotic activity observed; 1, 1–19 mitotic figures per
10 HPF; and 2, 20 or more mitotic figures per 10 HPF).
The salient cytological features of all three Grades of me-
ningioma were reviewed on CP and are summarized in
Table II. Grade I: the smears were hypercellular (72 of
72 cases). There were syncitial large tissue fragments,
arranged as clusters, whorls, or sheets (72 of 72 cases) as
shown in Figure 1. Papillary configuration were also
noted (29 of 72 cases) as shown in Figure 2. The cells
within these tissue fragments were polygonal to spindle
with eosinophilic and wispy cytoplasm (72 of 72 cases).
Nuclei were oval, sharply outlined, and slightly eccentric
(72 of 72 cases). Nuclear chromatin was homogeneous
and evenly distributed (72 of 72 cases). Small centrally
placed nucleoli were also present (68 of 72 cases). Nu-
clear grooves and cytoplasmic pseudoinclusions were also
identified (42 of 72 cases). Single polygonal and spindle
cells with wispy cytoplasmic prolongations were also
present in the background (70 of 72 cases). Scattered na-
ked nuclei were also observed in the background (62 of
72 cases). Mitotic activity was scored 0 in all cases. Kar-
yorrhexis and necrosis were also absent (0 of 72 cases).
Grade II: the smears were hypercellular with a prominent
sheet like architecture with whorls and clusters (22 of
22 cases) as shown in Figure 3. The cells were polygonal
with scant cytoplasm, which was wispy and granular (21
of 22 cases). The nuclei were slightly eccentric and
showed slight pleomorphism (19 of 22 cases). The nucle-
oli were central and large (18 of 22 cases). Mitotic activ-
ity was also seen in two (scored as 1 in first case and 2 in
the second case) of 22 cases. No evidence of necrosis
was identified in any case (0 of 22 cases). Single cells as
well as naked nuclei were also seen (9 of 22 cases). Nu-
clear grooves and nuclear pseudoinclusions were also
present (12 of 22 cases). Grade III: the smears were
hypercellular (13 of 13 cases). Clusters and whorls of
pleomorphic cells as well as single cells were present (13
of 13 cases). The cells had scant cytoplasm and a high
nucleus to cytoplasmic ratio (12 of 13 cases) as shown in
Figure 4. Prominent nucleoli were also commonly identi-
fied (11 of 13 cases). Mitotic activity was very frequent
in 10 (scored as 1 in one case and 2 in the remaining
9 cases) of 13 cases. Hemorrhage and necrosis were also
present (11 of 13 cases).
Discussion
Meningioma is one of the most common primary tumors
of the central nervous system. They are generally slow-
growing tumors and may be found very infrequently in
ectopic locations.8,9 They account for 13–26% of all pri-
mary intracranial tumors with an annual incidence rate
of *6/100,000 population.10 Meningiomas rarely meta-
stasize, which occurs in less than 1% of cases.11 Local
recurrence is a major cause of complications and death
in meningiomas.12 Metastasis often occurs only after the
local control has been lost.13 On the other hand, there
have been examples of ‘‘benign metastasizing meningio-
mas’’ with Grade I histologic characteristics and an indo-
lent clinical course.11,14,15 In view of these findings, it
has been suggested that the histological characteristics
and Grade of the metastatic tumor, rather than the fact
that there is metastatic disease, may be more pertinent to
the clinical outcome. Thus, histological grade is impor-
tant to determine clinical outcome when considering
meningiomas.
The aim of our study was to assess the usefulness and
accuracy of cytologic smears by making CP for grading
meningiomas. CP is commonly used for diagnosing neu-
ropathologic specimens intraoperatively. Shukla et al.16 in
their study include 278 patients with central nervous sys-
tem tumors, for whom CP was used. Two forty-four of
278 patients showed correlation with final histological di-
agnosis, giving the diagnostic accuracy of 87.76% for
usage of CP, in their study. Also, it needs to be men-
tioned that CP is almost always used as an add-on to fro-
zen sections, unless the submitted material is very limited,
when only a CP may be prepared from the limited tissue.
Numerous reports describing cytologic features of me-
ningioma have been published in the literature.17–19 In
our study, 107 meningioma cases were reviewed to assess
the cytologic features of meningiomas to assess for grad-
ing purposes. In all the cases, CPs were made and cyto-
logic diagnosis was correlated with final histologic diag-
nosis. Grade-I meningioma is usually easy to recognize
cytologically on CP.17–19 The key features seen in Grade-
I meningiomas in our study were hypercellularity without
evidence of necrosis. Mitotic activity was also scored as 0
(Fig. 1). The cells within these tissue fragments were po-
lygonal with eosinophilic cytoplasm. The nuclei were
oval with small central nucleoli. Numerous single cells in
the background were also present, which were mostly po-
lygonal with wispy cytoplasmic prolongations. Very often,
the cytoplasmic prolongations were of fibrillary quality. A
few of these single cells had hyperchromatic nuclei.
Table I. Distribution of Meningiomas in Various Body Locations
Location of tumor No. of cases % of total
Intracranial meningioma 92 85.9Spinal cord meningioma 11 10.2Orbital meningioma 3 2.8Olfactory groove meningioma 1 0.93
ALI ET AL.
828 Diagnostic Cytopathology, Vol 36, No 11
Diagnostic Cytopathology DOI 10.1002/dc
Table II. Salient Cytological Features of Meningioma
Cytologic features of meningioma Grade I Grade II Grade III
Cellular architectureCellularity Hypercellular Hypercellular HypercellularCell shape Polygonal to spindle Polygonal PleomorphicMitotic activity No mitotic activity (score ¼ 0) Mitotic activity in few
cells (score ¼ 1 to 2)Mitotic activity very frequent(score ¼ 2, rarely 1)
Necrosis No necrosis No necrosis Frequent necrosisCytoplasm
Cytoplasmic pattern Eosinophilic Granular ScantNucleus
Shape Oval Pleomorphic PleomorphicNucleolus Small central Large eccentric Prominent
Comparison of cytologic features of Grades I–III.
Fig. 1. CP of a Grade I meningioma showing whorls with polygonalcells with intranuclear inclusions and abundant eosinophilic cytoplasm(H&E 340). [Color figure can be viewed in the online issue, which isavailable at www.interscience.wiley.com.]
Fig. 2. Grade I meningioma showing a papillary configuration with pali-sading nuclei, some of which are naked (H&E 340). [Color figure canbe viewed in the online issue, which is available at www.interscience.wiley.com.]
Fig. 3. CP of a Grade II meningioma with hypercellular smear withclusters of cells showing mild to moderate degree of nuclear pleomor-phism (H&E 360). [Color figure can be viewed in the online issue,which is available at www.interscience.wiley.com.]
Fig. 4. Grade III meningioma with necrosis and abundant pleomorphiccells dispersed singly (H&E 360). [Color figure can be viewed in theonline issue, which is available at www.interscience.wiley.com.]
CRUSH PREPARATIONS OF MENINGIOMAS
Diagnostic Cytopathology, Vol 36, No 11 829
Diagnostic Cytopathology DOI 10.1002/dc
Papillary configurations (29 of 72 cases) and cytoplasmic
pseudoinclusions along with nuclear grooves (42 of
72 cases) were also identified in Grade-I meningiomas
(Fig. 2). These papillary configurations and cytoplasmic
pseudoinclusions can pose a possible pitfall, because
they have also been found in other tumors, including
papillary carcinoma of the thyroid.20 Cellular whorls
were also seen in Grade-I meningiomas in our study
(66 of 72 cases). These are a common cytologic feature
in Grade-I meningiomas, and sometimes can be confused
with the keratin pearls commonly seen in squamous cell
carcinomas and may also pose as a possible pitfall in
diagnosis.21
Grade-II meningiomas also exhibited hypercellularity,
and large tissue fragments were noted on CP. The cells
were arranged as whorls and clusters (22 of 22 cases).
Papillary configurations were virtually absent in Grade-II
meningiomas. The cells were polygonal with slightly less
cytoplasm when compared with Grade I. The cytoplasm
in Grade-II lesions was somewhat wispy and granular (21
of 22 cases) in contrast to the eosinophilic cytoplasm
seen in Grade I (Fig. 3). The nuclei in Grade II were also
slightly larger, and more eccentrically placed, than those
seen in Grade I. Slight pleomorphism of nuclei was also
more apparent in Grade II (19 of 22 cases). Nuclear
grooves and pseudoinclusions were also present in Grade
II (12 of 22 cases). The nucleoli were more centrally
placed and slightly larger than those seen in Grade I (18 of
22 cases). However, smaller nucleoli in a cellular group
were noted in all cases of Grade II. Single intact tumor
cells as well as naked nuclei were also present in Grade II;
however, these were seen in fewer cases when compared
with Grade-I meningiomas. Mitotic activity was observed
in only 2 of the 22 Grade-II cases and given a score of 1
and 2, respectively, for the two cases. This was helpful in
differentiating Grade II from Grade-1 cases, where the
cases reviewed each had a score of 0 for mitotic activity.
No necrosis was identified in any of the Grade-II cases,
which was found to be similar to Grade-I CP.
Grade-III meningiomas share some cytological features
with Grade-II meningiomas, such as hypercellularity, mi-
totic activity, and pleomorphic nuclei with large promi-
nent nucleoli.
The cells were pleomorphic and clearly malignant
appearing in all Grade-III CP that were reviewed in our
study (Fig. 4). These cases were relatively easier to iden-
tify on CP alone, because mitotic activity was very com-
mon. In 10 of 13 cases, mitotic activity was noted, and of
these 10 cases, only one case had a score of 1, whereas
the remaining 9 had a score of 2. Hemorrhage and necro-
sis were additionally noted in 11 of 13 cases. However,
the main overlapping cytologic features with Grade-II me-
ningiomas were the tumor cells, which were also polygo-
nal, and showed a large nucleus with scant cytoplasm.
The above review of cytologic features of Grades I–III
would be very helpful in grading meningiomas on CP.
However, in clinical practice, potential errors in grading
due to the process of embolization may be encountered.
Embolization of meningiomas is used sometimes preoper-
atively to minimize intraoperative bleeding. Embolization
brings on some histological changes that may lead to
overgrading the tumor, including macronucleoli, necrosis,
and compensatory proliferation with increased numbers of
mitotic figures.22–24 Communication between the neuro-
surgeon and neuropathologist regarding the use of emboli-
zation can reduce the risk of overgrading. Similarly,
knowledge of the patient’s history of radiation therapy
will prevent undue concern over necrosis or cellular
atypia.
In the past 5–10 years, there has been a considerable
progress in the understanding of the biology of meningi-
oma. The concept of prognosis and recurrence of manin-
gioma are a subject of great significance. Several markers
can actually be used as prognostic indicators in meningio-
mas and may allow a more individualized management of
patients. Two of the most important factors that determine
the prognosis in patients with meningioma are the extent
of the resection and the tumor’s histological Grade.
Higher grade meningiomas are more likely not to receive
a gross total resection, and even when they do, there may
still be recurrence.25,26 As an example, the authors of one
study found that within 5 years of resection, 12% of be-
nign meningiomas recurred compared with 41% of Grade-
II tumors.27 In another study, atypical meningioma (Grade
II) displayed a significant 10-year recurrence rate of 66%,
compared with 2% for a benign meningioma (Grade I).28
Once a tumor recurs, it is more likely to do so again, ulti-
mately leading to a loss of local control and rarely, me-
tastasis.29 Investigators at the Mayo Clinic have partially
dealt with these problems by clarifying the significance of
brain invasion and developing objective criteria that
allows reproducible grading of meningiomas, histologi-
cally. The investigators examined the correlation between
numerous parameters that include various histological fea-
tures (mitotic figures, sheeting, prominent nucleoli, hyper-
cellularity, and formation of small cells), brain invasion,
and progression-free survival.14,27 A few studies have
focused on minimal cytological details such as excessive
mitotic activity (20 or more mitotic figures per 10 HPF)
and anaplasia to be presumed as important prognostic cri-
teria.14,30 These details can also help in evaluating the CP
of meningiomas, especially in very small samples.
The revised and updated WHO classification is also a
major innovation in the histopathology of meningiomas.
This allows one to make a better assessment of the recur-
rence and infiltrative behavior of these tumors.31 This text
can be used for future studies with larger case numbers
for elaborating on the cytologic features of meningiomas.
ALI ET AL.
830 Diagnostic Cytopathology, Vol 36, No 11
Diagnostic Cytopathology DOI 10.1002/dc
In conclusion, it is possible to diagnose these tumors by
using CP. The grading can also be accomplished if partic-
ular attention is paid to the distinguishing cytomorpholog-
ical features in correlation with clinic radiological find-
ings and cytochemistry. It should be borne in mind that
on CP alone, there may be a considerable overlap in the
features seen in Grades I and II. However, Grade III may
be the easiest to diagnose on CP alone. Scoring mitotic
activity may also may helpful, which we, in our study,
found to be low (0) for Grade-I cases and high (predomi-
nantly 2) for Grade-III cases. Additional studies powered
by a higher number of cases that include clinical follow-
up data are needed to achieve a better understanding of
the subject. Furthermore, these data may improve our
ability to devise new therapeutic targets for the eradica-
tion of aggressive meningiomas.
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