Case 2 -
Calcifying Pseudoneoplasm of the Neural Axis
Thomas J. Cummings
Duke University Medical Center
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An otherwise healthy 43-year-old male presented with a one-year history of persistent neck pain that
often awoke him from sleep. There was no history of trauma. On physical examination, his neck had
limited range of motion. Pain was elicited on lateral rotation. The remainder of the neurological
examination was unremarkable. MRI of the cervical spine showed a 1.8 x 1.7 cm intradural,
extramedullary, heterogeneously enhancing mass at the level of the foramen magnum. There was mass-effect
upon the cervical spinal cord and medulla with displacement of the spinal cord to the left. There was no
evidence of a dural tail or extension along nerve roots. The remainder of the posterior fossa was
unremarkable. The mass demonstrated internal hypointense T1 and T2 signal,
consistent with either hemosiderin or calcification. The leading radiographic differential consideration
was a partially calcified meningioma. An intradural, extramedullary cavernous hemangioma was considered
less likely. The patient underwent a suboccipital craniectomy and C1 laminectomy. Intraoperatively, the
tumor was described as "rock hard" and was removed in a piecemeal manner using a diamond drill.
Postoperatively, the patient is doing well. Follow-up MRI shows no evidence of recurrence one year
Case 2 - Slide 1
Case 2 - Figure 1
Sagittal T1-weighted, contrast-enhanced MRI of the cervical spine shows a lesion at the level of the foramen magnum.
Case 2 - Figure 2
Sagittal T2-weighted MRI of the cervical spine shows the foramen magnum lesion.
Case 2 - Figure 3
Axial T2-weighted image showing mass effect on the upper cervical spinal cord.
Case 2 - Figure 4
The lesion exhibited multiple lobules with a hypocellular chondromyxoid matrix and a granulomatous-like appearance rimmed by palisading spindled/round cells (H&E x 4).
Case 2 - Figure 5
Higher magnification showing the hypocellular lobules rimmed by spindled cells (H&E x 20).
Case 2 - Figure 6
Areas of the lesion were ossified and calcified and showed a deeply basophilic appearance (H&E x 10).
Case 2 - Figure 7
High magnification showing coarse fibrillar basophilic material within the nodules and surrounded by spindled cells (H&E x 40).
Case 2 - Figure 8
Alcian blue histochemical stain shows positive staining of the matrix within the lobules.
Case 2 - Figure 9
Adjacent to some of the lobules were proliferations of spindled cells with occasional whorl structures among numerous blood vessels (H&E x 40).
Case 2 - Figure 10
An epithelial membrane antigen immunohistochemical stain highlights the spindle
Calcifying Pseudoneoplasm of the Neural Axis
Calcifying pseudoneoplasm of the neural axis is an uncommon lesion that usually arises from the
craniospinal meninges or the bones of the spine
. Most cases are sporadic.
The lesion is typically slow-growing and with gross total excision the prognosis is excellent. The
etiology and pathogenesis of this lesion is still unknown, but likely represents a reactive rather than a
neoplastic process. The preoperative diagnosis is usually not suggested, since by MRI these lesions most
resemble meningioma. In the current case the leading MRI considerations were calcified meningioma and
extramedullary cavernoma. Intraoperatively, the surgeon strongly favored this being a calcified
The microscopic features of calcifying pseudoneoplasms are usually quite typical. They are
characterized by a multinodular appearance. They contain an eosinophilic chondromyxoid and coarsely
fibrillar matrix admixed with ossification and fibrovascular tissue. The nodules are often rimmed by a
peripheral palisade of spindled, rounded, stellate, cuboidal or multinucleated giant cells, some of which
may be embedded within the hypocellular center of the nodules . A helpful clue to the diagnosis is
the histologic appearance of the chondromyxoid matrix with a coarsely fibrillar interlacing pattern
(likened to "chicken foot prints") surrounding a central amorphous pattern with embedded stellate cells.
A range of calcification and ossification may vary among cases and may present as granular/particulate
calcifications, frank lamellar bone formation, both or neither.
Focal granulation tissue with hemosiderin was seen in our case. Adjacent to the nodules and embedded
within the tissue were psammoma bodies and meningothelium with whorl formations similar to meningioma. A
histochemical stain for alcian blue highlighted the chondromyxoid matrix. Congo red was negative for
amyloid, and a monosodium urate stain was negative for crystals. The spindle and cuboidal cells were
immunoreactive for vimentin and epithelial membrane antigen. An immunostain for glial fibrillary acidic
protein was negative. The Mib-1 index was low.
Despite this characteristic histopathologic appearance, if the pathologist is not familiar with this
entity a wide range of potentially neoplastic, inflammatory or granulomatous considerations may enter the
differential diagnosis, including meningioma with metaplastic ossification, granulomatous inflammation,
calcium pyrophosphate (pseudogout), and other mesenchymal tumors . These cases are often associated
with a meningothelial hyperplasia that can be mistaken for meningioma, especially if a small, fortuitous
biopsy is performed, especially at the time of frozen section // intraoperative consultation. A rare
case of calcifying pseudoneoplasm has been reported in association with a cerebellar ependymoma, and the
pseudoneoplasm was thought to represent an unusual tumefactive reaction to the tumor . Although the
pathogenesis is not completely understood, some have suggested that the calcifying pseudotumor of the
neural axis represents an unusual expression of tumoral calcinosis or abortive membranous bone formation
with osseous neoplasia .
Take Home Points
- Unusual tumefactive lesions can arise along the craniospinal axis
- Clinically they are often worrisome for a neoplastic
- Tumefactive lesions can
present diagnostic challenges when they exhibit histologic features that overlap with neoplastic,
inflammatory or granulomatous processes
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