Case 2 -

Calcifying Pseudoneoplasm of the Neural Axis Thomas J. Cummings Duke University Medical Center Durham, NC

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Click here to view (or print) handout in single page format. (4.76 MB) Note: Any slides will be printed in color. Clinical History: 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 later. Case 2 - Slide 1 Click to view with ImageScope Click to view with a Web-Based Viewer 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 Diagnosis Calcifying Pseudoneoplasm of the Neural Axis Discussion Calcifying pseudoneoplasm of the neural axis is an uncommon lesion that usually arises from the craniospinal meninges or the bones of the spine [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12] . 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 meningioma. 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 [8]. 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 [8]. 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 [10]. 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 [8]. Take Home Points Unusual tumefactive lesions can arise along the craniospinal axis Clinically they are often worrisome for a neoplastic process Tumefactive lesions can present diagnostic challenges when they exhibit histologic features that overlap with neoplastic, inflammatory or granulomatous processes Reference List Bertoni F, Unni KK, Dahlin DC et al. Calcifying pseudoneoplasms of the neural axis. J Neurosurg 1990, 72 (1), 42-48. Chang H, Park JB, and Kim KW. Intraosseous calcifying pseudotumor of the axis: a case report. Spine 2000, 25 (8), 1036-1039. Garen PD, Powers JM, King JS et al. Intracranial fibro-osseous lesion. Case report. J Neurosurg 1989, 70 (3), 475-477. Halper J, Scheithauer BW, Okazaki H et al. Meningio-angiomatosis: a report of six cases with special reference to the occurrence of neurofibrillary tangles. J Neuropathol Exp Neurol 1986, 45 (4), 426-446. Jun C and Burdick B. An unusual fibro-osseous lesion of the brain. Case report. J Neurosurg 1984, 60 (6), 1308-1311. Moser FG, Tourje EJ, Pressman BD et al. Calcifying pseudotumor of the cervical spine. AJNR Am J Neuroradiol 1994, 15 (3), 580. Perry A. Meningiomas. In: McLendon RE, Rosenblum MK, and Bigner DD. Russell & Runbinstein's Pathology of Tumors of the Nervous System 7th ed. London: Hodder Arnold, 2006: 427-474. Qian J, Rubio A, Powers JM et al. Fibro-osseous lesions of the central nervous system: report of four cases and literature review. Am J Surg Pathol 1999, 23 (10), 1270-1275. Rhodes RH and Davis RL. An unusual fibro-osseous component in intracranial lesions. Hum Pathol 1978, 9 (3), 309-319. Rodriguez FJ, Scheithauer BW, Fourney DR et al. Ependymoma and intraparenchymal calcifying pseudoneoplasm of the neural axis: incidental collision or unique reactive phenomenon? Acta Neuropathol (Berl) 2007, [Epub ahead of print] Smith DM and Berry AD, III. Unusual fibro-osseous lesion of the spinal cord with positive staining for glial fibrillary acidic protein and radiological progression: a case report. Hum Pathol 1994, 25 (8), 835-838. Tatke M, Singh AK, and Gupta V. Calcifying pseudoneoplasm of the CNS. Br J Neurosurg 2001, 15 (6), 521-523.