A Case Report of Calcifying Pseudoneoplasm of the Neuraxis: An Incidental Finding After a Car Accident
Farahnaz Bidari ZEREHPOOSH1, Mohammad SAMADIAN2, Vahideh Sadat AZHARI1, Maryam BARANGI1, Kaveh EBRAHIMZADEH2, Mahnaz HEIDARY1
1Department of Pathology, Loghman Hospital, tehran, Iran
2Department of Neurosurgery, Loghman Hospital, tehran, Iran
Calcifying pseudoneoplasms of the neuraxis are rare, poorly understood lesions that can occur anywhere in the central nervous system without
any age or sex predilection. Their pathogenesis is still controversial. Patients can present with various symptoms due to lesion location and only
few cases have been discovered incidentally. We present a 25-year-old male referred to our hospital after a car accident. Computed tomography
scan and magnetic resonance imaging was done because of the patient's head trauma and a calcified intracranial lesion was found and excised
surgically. Pathologic evaluation of the specimen was consistent with the diagnosis of calcifying pseudoneoplasm of the neuraxis.
Calcifying pseudoneoplasms of the neuraxis (CAPNONs),
which are variably named as fibro-osseous lesions, cerebral
calculi, brain stones or calcifying pseudotumors, are rare
lesions that were first reported by Miller in 1922 (1); since
then, 56 cases have been reported in international literature
(1), none of them in the middle-eastern population.
These lesions are typically benign, slow growing and non
infiltrative, although their pathogenesis is controversial
and various authors have considered them as metaplastic or
reactive lesions (1,2).
CAPNONs can occur anywhere within the neuraxis,
intracranial or spinal, intra-axial or extra-axial (1-3).
Although typically benign, symptoms of CAPNONs
typically present secondary to compression and surrounding
mass effect (4). Various symptoms and signs will therefore
appear according to their location. Intracranial ones often
present with headache, seizure and/or other symptoms
related to the local compressive effect of the mass (1,2);
on the other hand spinal lesions commonly present with
localized pain in the affected area (1). Only 3 out of 56
reported patients were incidentally found (8.1%) (1). In
this report we describe an intra-axial lesion in the temporal
lobe which was an incidental finding during diagnostic
procedures in a car accident case.
A 25-year-old man with a healthy past history and no
previous neurological problem suffered a car accident
and underwent a computed tomography (CT) scan which
was followed by a magnetic resonance imaging (MRI)
scan. CT scan revealed a 3 cm calcified ovaloid mass in
the left medial temporal region that was suspected to be
a meningioma (Figure 1
). T1 and T2W MRI showed a
hypointense mass in the left medial temporal lobe with
heterogenous enhancement of the lesion (Figure 2
patient elected to undergo mass resection surgery. After
general anesthesia in the left lateral decubitus position, left
temporal craniotomy was performed. The surgical approach
was through an inferior temporal gyrus corridor, and after
microsurgical dissection of the inferior temporal gyrus
the calcified mass was totally resected. The postoperative
period was uneventful and the patient is now well after 3
Microscopic examination revealed amorphous calcification
and psammoma bodies with foci of ossification in the
brain tissue (Figure 5
) and a loose fibromyxoid stroma in
some parts that contained scattered blood vessels (Figure
). Calcified areas were sometimes surrounded by cells
resembling meningothelial cells and also palisaded spindle
cells and few multinucleated giant cells. No epithelial
component was seen.
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|Figure 1: Axial bone window CT scan showed a calcifying mass
in left medial temporal region.
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|Figure 2: Axial T1W MRI with Gd revealed heterogenous
enhancement of the lesion.
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|Figure 3: Axial T1W MRI showed a hypointense mass in the left
medial temporal lobe.
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|Figure 4: Axial T2W MRI showed a hypointense mass in the left
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|Figure 5: Psammomatous calcification with foci of ossification in
brain tissue and no epithelial component (H&E; x100).
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|Figure 6: The fibromyxoid stroma contained scattered blood
vessels and areas of amorphous granular calcification surrounded
by spindle cells (H&E; x100).
Immunohistochemical staining was performed using
commercially (DAKO), available antibodies against EMA,
NSE, S-100, vimentin, CD68 and glial fibrillary acidic
protein (GFAP). Tumor cells were negative for epithelial
membrane antigen (EMA), neuron specific enolase (NSE),
S-100 protein and GFAP. Few vimentin and CD68 positive
cells are seen scattered in the surrounding calcified areas.
The final diagnosis was calcifying pseudoneoplasm of the
CAPNONs are rare lesions arising anywhere in the central
nervous system (CNS) (1-3,5). These lesions are intraaxial
or extraaxial (1), and mostly dural-based (7); intracranial
ones often involve the leptomeninges whereas spinal cases
generally involve paraspinous meninges, soft tissue and
bone (8). CAPNONs have been mentioned in the literature
since 1922 as unusual fibro-osseous lesions of the brain
(1,6). They were recognized as a distinct entity in 1978 and
there are 40 international reported cases (1,7,9).
Most of the published articles mention no sex or age
predominance with an age range of 6-83 years (1,3).
Headache and seizure are the most common symptoms
in intracranial lesions and only few cases are discovered
incidentally (1,2). The typical lesion is sporadic, but
some CNS lesions have occurred in association with
meningioangiomatosis in patients with neurofibromatosis
type 2 (8).
The original tissue is controversial; a meningothelial origin
is suspected in dural-base lesions while the hard dense
fibrous stroma and the spindle cell population make a
mesenchymal origin another possibility (3,7).
The pathogenesis of CAPNON is not well understood
but based on the available data a reactive process is more
possible than neoplastic ones (1). It has been suggested,
but not proven, that CAPNON may develop as a response
to multiple inciting factors, which can account for the
variations in histopathologic features. The causal factors
are not yet understood, but response to possible trauma,
infection, or inflammation has been proposed (3).
In a few cases, CAPNONs have been reported in combination
with neoplasms such as ganglioglioma or dysembryoplastic
neuroepithelial tumor (2,10).
On imaging, they can easily be confused with malignant
lesions such as chondrosarcoma or chondroblastoma or
even more benign pathologies such as meningioma (4).
CT images typically show solid areas of calcification and
MR imaging often shows a well-defined lesion that is
hypointense in T1 and T2-weighted images without any brain edema. Contrast enhancement is limited to minimal
linear internal or rim enhancement (1,11).
The above CT and MRI findings were also seen in
this presented case but with heterogenous contrast
enhancement. Surprisingly similar CT and MRI findings to
those of our case were seen in the case reported by Pereira
et al. as a choroid plexus papilloma with osseous metaplasia
and this similarity should be kept in mind in the differential
diagnosis of such imaging presentations (11).
The classic histopathological features of CAPNON include
a set of common elements: 1) presence of chondromyxoid
matrix in a nodular pattern; 2) palisading spindle to
epithelioid cells; 3) fibroblastic proliferation; 4) amorphous
calcification, psammoma bodies and osseous metaplasia;
5) foreign-body reaction with giant cells surrounding the
calcified region (1,3,7). These pathological presentations
are not evident in each case and some lesions may not show
all of the above features (3). Our presented case revealed
all of the abovementioned histopathological features except
for the nodular chondromyxoid matrix.
The microscopic differential diagnosis of CAPNON includes
a variety of reactive lesions such as granulomatous
diseases, herniated disc material, and some neoplastic
lesions such as chondroid chordoma, chondroma,
chondrosarcoma, metaplastic meningioma, choroid plexus
papilloma with osseous metaplasia and calcified primary
parenchymal central nervous system tumors (1,11).
A wide variety of immunohistochemical stains have been
used to characterize CAPNONs. The majority of recent reports have focused on S100 protein, vimentin, EMA, and
GFAP (1,2). All CAPNONs stained positive for vimentin,
most stained positive for EMA, and were negative for S100
and GFAP. A minority of cases stained positive for S100,
were negative for EMA, and 1 case stained positive for
The distinctive histopathology of CAPNON makes it
easy to diagnose for expert pathologists. To the unwary,
however, it can be mistaken for other tumors with extensive
calcification, such as psammomatous meningioma.
Calcifications in meningioma are smaller, round, and
lamellated in contrast to the large, irregular calcifications
of CAPNON. Choroid plexus papilloma with osseous
metaplasia can be differentiated from CAPNON with the
presence of epithelial components (11). Spinal lesions may
mimic calcified tuberculosis, but CAPNON does not form
granulomas, despite nodules of peripheral cellularity and
occasional giant cells (8).
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