Prostaglandin D Synthase (?-Trace) in Meningeal
Masatou Kawashima, M.D., Satoshi O. Suzuki, M.D., Ph.D., Tetsumori Yamashima, M.D., Ph.D.,
Masashi Fukui, M.D., Ph.D., Toru Iwaki, M.D., Ph.D.
From the Departments of Neuropathology (MK, SOS, TI) and Neurosurgery (MK, MF), Neurological
Institute, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; and the Department
of Neurosurgery, Kanazawa University, School of Medicine, Kanazawa, Japan (TY)
The level of prostaglandin D synthase (PGDS), a
major protein constituent of cerebrospinal fluid
(CSF), is altered in various brain diseases, including
meningitis. However, its role in the brain remains
unclear. PGDS is mainly synthesized in the arach-
noid cells, the choroid plexus and oligodendrocytes
in the central nervous system. Among brain tumors,
meningiomas showed intense immunoreactivity to
PGDS in the perinuclear region. Thus, PGDS has
been considered a specific cell marker of meningi-
oma. In this study, we examined 25 meningeal he-
tumors (64%) showed immunoreactivity for PGDS
in the perinuclear region. For comparison, 15 me-
ningiomas, 14 soft-tissue HPCs, 1 mesenchymal
chondrosarcoma, 3 choroid plexus papillomas, and
7 oligodendrogliomas were also examined. Menin-
in 13 cases (80%). Except for one case located at the
sacrum, none of the other soft-tissue HPCs showed
immunostaining for PGDS. Mesenchymal chondro-
sarcoma arises in the bones of the skull, and its
histological pattern resembles that of HPC; how-
ever, it showed no immunoreactivity for PGDS. Nei-
ther choroid plexus papillomas nor oligodendrogli-
omas were immunopositive for PGDS. These
findings suggest that meningeal HPCs may have a
unique molecular phenotype that is distinct from
HPCs may be more closely related to the arachnoid
KEY WORDS: Arachnoid cells, Immunohistochem-
istry, Meningial hemangiopericytoma, Meningi-
oma, Prostaglandin D synthase.
Mod Pathol 2001;14(3):197–201
Meningeal hemangiopericytoma (HPC), formerly
regarded as a variant of angioblastic meningioma,
represents an uncommon type of perivascular soft-
tissue tumor (1). In 1942, Stout and Murray (2)
identified a soft-tissue tumor located primarily in
the thigh, buttock, and retroperitoneum that
seemed to consist of proliferating pericytes and
called it a hemangiopericytoma. Begg and Garrett
(3) first reported a meningeal HPC in 1954. They
reviewed six angioblastic meningiomas from Cush-
ing’s series and concluded that they were actually
HPCs arising from within the meninges. Today,
most pathologists are convinced that meningeal
HPC and soft-tissue HPC are similar (4). Therefore,
meningeal HPC is thought to be a pericytic tumor
Prostaglandin D synthase (PGDS) [prostaglandin
H2D isomerase; (5Z,13E)-(15S)-9,11-epidioxy-15-
126.96.36.199] is a brain-specific glycoprotein that regu-
lates sleep through the synthesis of PGD2. PGDS is
a member of the lipocalin superfamily composed of
various secretory lipophilic ligand-carrier proteins
(5–7). PGDS and its mRNA are mainly synthesized
in the arachnoid cells, the choroid plexus, and oli-
godendrocytes in the central nervous system (8–
10). In brain tumors, only meningioma cells have
been proved to show intense immunoreactivity to
PGDS in the perinuclear region (10). PGDS has thus
been considered a specific cell marker of meningi-
oma. The present study presents an immunohisto-
chemical comparison of 25 meningeal HPCs, 15
meningiomas, 14 soft-tissue HPCs, 1 mesenchymal
chondrosarcoma, 3 choroid plexus papillomas
(CPPs), and 8 oligodendrogliomas with respect to
the brain-specific protein PGDS.
Copyright © 2001 by The United States and Canadian Academy of
VOL. 14, NO. 3, P. 197, 2001 Printed in the U.S.A.
Date of acceptance: November 27, 2000.
Address reprint requests to: Masatou Kawashima, Department of Neuro-
pathology, Neurological Institute, Graduate School of Medical Sciences,
firstname.lastname@example.org; fax: ?81-92-642-5540.
MATERIALS AND METHODS
The tumor samples listed in Table 1 were ob-
tained at surgery from 23 patients (17 male and 6
female, including two recurrent cases; ranging in
age from 13–66 y) at the Department of Neurosur-
gery, Kyushu University Hospital. The tumor sam-
ples listed in Tables 2–4 were also submitted at
surgery from 14 patients in Table 2 (8 male and 6
female; ranging in age from 0–65 y), 1 patient in
Table 3 (male; 12 years old) and 15 patients in Table
4 (4 male and 11 female; ranging in age from 41–83
y) at the Departments of Surgery, Orthopedics, and
Neurosurgery, Kyushu University Hospital. Three
CPPs (from one male and two female patients rang-
ing in age from 17–67 y) and seven oligodendrogli-
omas (from six male and one female patients rang-
ing in age from 31–69 y) were also obtained at the
Department of Neurosurgery, Kyushu University
Hospital. To assure optimal immunoreactivities,
only those tumors resected after 1975 were in-
cluded in the study.
Immunohistochemistry for PGDS was performed
on paraffin sections of brain tumors and soft-tissue
HPCs by the indirect immunoperoxidase method.
Surgical specimens of the tumors were fixed in
10% buffered formalin overnight and embedded in
paraffin. The samples were then cut into 5-?m sec-
tions. The sections were deparaffinized in xylene
and hydrated in an ethanol gradient. The endoge-
nous peroxidase activity was blocked with 0.3%
H2O2in absolute methanol for 30 minutes at room
temperature. The sections were then washed in TB
(50 mM Tris-HCl, pH 7.6), followed by overnight
incubation with the PGDS antibody (1:2000 dilu-
tion, kindly supplied by Mr. Oda, Central Research
Institute, Maruha Corporation, Tsukuba, Japan) at
4°C. After being washed in TB, the sections were
incubated with horseradish peroxidase-conjugated
secondary antibody (1:200 dilution, Vector Labora-
tories, Burlingame, CA). The colored reaction prod-
uct was developed with 3,3'-diaminobenzidine tet-
rahydrochloride (3,3'-diaminobenzidine) solution.
The sections were counterstained lightly with he-
matoxylin. The tests were done together with an
appropriate positive control (meningioma).
The specificity of the polyclonal antibody against
PGDS in tumor tissue was assessed using a soluble
fraction extracted from frozen tumor samples of
meningeal HPCs and meningiomas. The samples
were homogenized in 1.5 volumes of buffer con-
taining 2% sodium dodecyl sulfate, 2 mM EDTA, 2
mM phenylmethylsulfonyl fluoride, 50 mM Tris-HCl,
pH 6.8. The protein concentrations were deter-
mined by a modified Lowry’s procedure using bo-
vine serum albumin as the protein standard. Lae-
mmli’s sample buffer was added to this mixture,
and the samples were boiled for 5 minutes. Each
protein sample (15 ?g per lane) was separated on
12% SDS-polyacrylamide gel and transferred to a
polyvinylidene difluoride membrane (Millipore,
Bedford, Massachusetts). After blocking with 5%
low-fat milk in TBST (25 mM Tris-HCl, pH 7.6; 0.15
M NaCl; 0.05% Tween 20; 0.05% NaN3), the mem-
brane was incubated at 4°C overnight with anti-
PGDS antibody (1:2000) in TBST containing 5%
low-fat milk. After it was washed, the filter was incu-
bated with the alkaline phosphatase-conjugated
secondary antibody (1:7500 dilution, Promega,
Madison, WI), and the blot was visualized by the
substrates of 5-bromo-4-chloro-3-indolyl phos-
phate and nitroblue tetrazolium.
TABLE 1. PGDS Immunoreactivity in Meningeal
LocationNumber of CasesPGDS Immunopositivity (%)
PGDS, prostaglandin D synthase.
TABLE 2. PGDS Immunoreactivity in Soft-Tissue
LocationNumber of CasesPGDS Immunopositivity (%)
1 (7) 14
PGDS, prostaglandin D synthase.
TABLE 4. PGDS Immunoreactivity in Meningiomas
Subtype Number of Cases PGDS Immunopositivity (%)
15 12 (80)
PGDS, prostaglandin D synthase.
TABLE 3. PGDS Immunoreactivity in Mesenchymal
Location Number of CasesPGDS Immunopositivity
PGDS, prostaglandin D synthase.
198 Modern Pathology
Of the 25 meningeal HPCs, 18 (72%) were supra-
tentorial, commonly parasagittal or falcial; 3 (12%)
were infratentorial, one each located in the
cerebello-pontine angle, jugular foramen, and tor-
cular Herophili; and 4 (16%) were in the thoracic
region (Table 1). No purely intraparenchymal HPC
was encountered. Fourteen soft-tissue HPCs were
located in a variety of somatic regions, including
four in the retroperitoneum; two in the femur; two
in the buttock; and a single case each from the
breast, shoulder, and anterior sacrum (Table 2). The
single case of mesenchymal chondrosarcoma was
located in the parietal region (Table 3). Fifteen
cases of meningioma consisted of four subtypes,
including seven meningothelial, three fibrous, three
transitional, and two secretory (Table 4). Among the
meningiomas, 12 cases were supratentorial.
Meningeal and soft-tissue HPCs were typical cel-
lular tumors composed of oval to slightly spindle
cells with oval, occasionally elongated nuclei (Fig.
1A). Nuclear atypia and mitosis were seen but var-
ied from case to case. The tumor cells grew as
monotonous sheets, interrupted by numerous slit-
like vascular spaces lined by flattened endothelial
cells. So-called staghorn sinusoids were identified
in all cases. Mesenchymal chondrosarcoma showed
a biphasic pattern of well-differentiated cartilage
alternating with cellular portions resembling an
HPC. Meningiomas had a wide range of histopatho-
logical appearances characteristic of the subtypes.
The results of our immunohistochemical analysis
for PGDS are summarized in Tables 1–4. Meningeal
HPCs were immunopositive for PGDS in 64% of all
cases examined (Table 1). Especially those in the su-
pratentorial region showed more frequent immuno-
reactivity (78%) than did those in either the infraten-
torial regions (33%) or the thoracic cord (25%).
Staining tended to be focal and patchy compared
with meningioma; however, perinuclear, granular cy-
toplasmic staining resembling meningioma was ob-
served (Fig. 1B). PGDS expression was observed in
neither soft-tissue HPC (Table 2, Fig. 1C) nor mesen-
chymal chondrosarcoma (Table 3), except for a single
case of soft-tissue HPC located at the sacrum (Fig.
1D). Meningioma showed higher frequency (80%) of
immunostaining for PGDS (Table 4). Typical staining
was observed around the perinuclei (Fig. 2, A–B). Two
cases of fibrous meningioma and one case of secre-
tory meningioma showed no immunoreactivity for
PGDS. Neither CPPs nor oligodendrogliomas were
immunopositive for PGDS.
FIGURE 1. Hemangiopericytomas of both meninges and soft tissue. A, meningeal hemangiopericytoma (HPC) is a cellular and vascular tumor
composed of round to oval cells with oval nuclei that is indistinguishable from soft-tissue HPC (HE). B, immunohistochemical staining for
prostaglandin D synthase (PGDS) in meningeal HPC reveals perinuclear, cytoplasmic immunoreactivity. C, soft-tissue HPC. Immunoreactivity for
PGDS is not observed. D, soft-tissue HPC of the sacrum. The tumor shows cytoplasmic staining for PGDS resembling meningeal HPC. (bar ? 50 ?m)
PGDS in Meningeal Hemangiopericytoma (M. Kawashima et al.) 199
The results of immunoblotting are shown in Fig-
ure 3. The extracts from meningeal HPCs (Lanes 1
and 2) showed a band (29 kDa) corresponding to
PGDS. Meningiomas (Lanes 3–5) also showed a
PGDS is the enzyme responsible for biosynthesis
of prostaglandin D2(PGD2) in the central nervous
system and is identical to a major CSF protein,
?-trace (11–13). PGD2had long been considered a
minor and biologically inactive prostanoid. In the
late 1970s, Hayaishi et al. (14) found large amounts
of PGDS in the brains of rat and other mammals,
including humans. PGD2circulates in the ventric-
ular system, subarachnoid space, and extracellular
spaces of the brain and interacts with receptors on
the ventromedial surface of the rostral basal fore-
brain to initiate the signal to let the brain sleep (15).
PGDS is a member of the lipocalin superfamily
composed of various secretory lipophilic ligand-
carrier proteins (6, 7). However, its primary role in
the brain remains unclear.
PGDS is mainly synthesized in the arachnoid
cells, the choroid plexus, and oligodendrocytes in
the central nervous system (8, 10). Recently PGDS
expression in testis and heart has been reported
(16, 17). PGDS mRNA is detected by in situ hybrid-
ization in mouse embryonic mesenchymal cells
destined to become arachnoid cells and later in the
developing testis (18).
PGDS in the CSF is altered in various brain dis-
eases, including meningitis, multiple sclerosis, sub-
arachnoid hemorrhage, and infarction (19, 20). A
recent report revealed that the level of PGDS in CSF
increased in various brain tumors (21). It may con-
tribute to regulate the permeability of the meninges
(20). PGDS has been considered a specific cell
marker of meningiomas. Meningioma cells showed
intense immunoreactivity in the perinuclear region,
and that was often concentrated within meningo-
cytic whorls and around calcifying psammoma
bodies (10). We also examined immunoreactivity
for PGDS in three CPPs and seven oligodendrogli-
omas because choroid plexus and oligodendrocytes
are weakly immunopositive for PGDS in the central
nervous system. They showed no immunoreactivity
for PGDS. Thus, we could strengthen the idea that
PGDS has a specificity for meningiomas.
In this study, meningeal HPC showed relatively
high frequency (64%) of immunoreactivity to PGDS.
Moreover, soft-tissue HPC showed no immuno-
staining for PGDS except for a single case at the
surface of the sacrum, which might be associated
with the meninges. Because the histological fea-
tures so common to meningeal HPC are often en-
countered in mesenchymal chondrosarcoma, the
tumor was also investigated for PGDS immunore-
activity. Because it is rare, only a single case was
investigated, and it proved to be immunonegative
for PGDS. These findings indicate that meningeal
and soft-tissue HPCs are distinctive in view of their
PGDS expression. PGDS is widely expressed in the
human body; however, the fact that only meningeal
HPCs express PGDS means that they may be more
closely related to arachnoid cells.
Meningioma and meningeal HPC are currently
classified as different entities, but both showed posi-
tive immunoreactivity for PGDS. These tumors
(10) presented 100% positive immunoreactivity for
PGDS in all meningioma cases, including meningo-
thelial, transitional, fibrous, angiomatous, and atypi-
cal meningiomas. In the present study, meningiomas
showed a lower frequency of immunopositivity (80%)
for PGDS than that observed by Yamashima et al.
Moreover, the cases that were immunonegative for
PGDS consisted of subtypes of fibrous and secretory
meningiomas. In transitional meningiomas, menin-
FIGURE 2. Meningothelial meningioma immunostained for
prostaglandin D synthase (PGDS). A and B, the tumor shows
perinuclear, cytoplasmic staining for PGDS similar to the positive
pattern in the meningeal hemangiopericytoma. (bar ? 50 ?m)
FIGURE 3. An immunoblot probed with anti–prostaglandin D
synthase (PGDS) polyclonal antibody. Lanes 1 and 2, meningeal
hemangiopericytomas (HPCs); Lanes 3, 4, and 5, meningiomas. The
extracts from meningeal HPCs and meningiomas showed a band (29
kDa) corresponding to PGDS. Prestained molecular weight standards
(by Bio-Rad, Hercules, California) are given in kilodaltons on the left.
200 Modern Pathology
gothelial cells with round to oval nuclei tended to be Download full-text
immunopositive for PGDS. The present study dem-
onstrated a 64% positive rate in meningeal HPCs,
which is a lower rate of positivity than that of menin-
giomas. When a meningeal HPC located in the supra-
tentorial region is compared with meningioma, the
difference of PGDS expression is not remarkable (78%
infratentorial meningiomas. The meningiomas that
showed negative immunoreactivity for PGDS were
supratentorial tumors. The positive rates of supraten-
torial HPCs and supratentorial meningiomas were al-
most the same (78% versus 75%). The common ex-
pressionof PGDS in
meningioma may be related to cranial mesenchymal
cells. In the central nervous system, primitive mesen-
chymal cells destined to become arachnoid cells or
pericytes exist. Recently, it was reported that multi-
potent mesenchymal stem cells were isolated from
adult bone marrow, and they were induced to differ-
entiate into a variety of mesenchymal tissues (22, 23).
In situ hybridization studies by Hoffmann et al. (18)
showed cellular localization of PGDS mRNA during
postconception, PGDS mRNA was found to be con-
densed only in the leptomeningeal cells of the brain
and spinal cord. Later, at 16.5 days postconception,
choroid plexus epithelial cells and single cells within
the brain parenchyma were labeled at a significantly
lower rate than arachnoid cells. These findings sug-
gest that PGDS plays a more important role in the
arachnoid cells than in the choroid plexus and brain
parenchyma (oligodendrocytes). It is speculated that
if they become neoplastic, PGDS expression may ac-
company the change. To test this hypothesis, PGDS
expression in primitive mesenchymal cells should be
In conclusion, meningeal HPCs may have a dis-
tinct molecular phenotype compared with soft-
tissue HPCs, and they are more closely related to
the arachnoid cells in origin.
Acknowledgments: We thank Prof. M. Tsuneyoshi
and Dr. Y. Oda for providing materials and comments,
Ms. K. Hatanaka for her excellent technical assistance,
and Ms. K. Ono for reviewing the manuscript.
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PGDS in Meningeal Hemangiopericytoma (M. Kawashima et al.)201