Presentation
Incidental finding.
Patient Data
A heavily calcified mass lesion arises from the inferior aspect of the fourth ventricle and bulges inferiorly to the craniocervical junction. There is mass effect over the posterior aspect of the lower medulla. The upper cervical cord is pushed towards the left.
A heavily calcified mass lesion arises from the inferior aspect of the fourth ventricle and bulges inferiorly to the craniocervical junction. It protrudes through the foramen of Luschka on the right. There is mass effect and slight oedema with in the posterior aspect of the lower medulla. The upper cervical cord is pushed towards the left. The lesion demonstrates contrast enhancement. It lies adjacent to and effaces the medial wall of the intradural right vertebral artery. The findings do not suggest that the lesion is a calcified aneurysm of the vertebral artery. No other mass lesions are identified. No hydrocephalus. Minor degenerative changes are noted within the cervical spine.
Conclusion: Heavily calcified mass lesion arising from the inferior aspect of the fourth ventricle and causing mild mass effect upon the posterior aspect of the medulla and upper cervical cord. The most likely diagnosis is ependymoma. Meningioma, calcified subependymoma is thought unlikely.
MACROSCOPIC DESCRIPTION: 1. "Brain tissue": Two fragments of gritty fawn tissue up to 8mm. 2. "Brain tumour": Red and pink fragment tissue 1mm aggregate. 3. "Posterior fossa brain tumour": Red and pink fragment tissue 25x10 x10mm aggregate. A1.
MICROSCOPIC DESCRIPTION: 1-3: Paraffin sections show multiple tissue fragments in which there is widespread deposition of crystalline partially calcified material, much of which is strongly birefringent. In many areas, deposits are surrounded by a population of spindle cells with moderate membrane immunostaining for epithelial membrane antigen (EMA). No perinuclear dot EMA reactivity is seen. The spindle cells are mixed with a lymphohistiocytic cell infiltrate. No immunostaining for GFAP, synaptophysin or progesterone receptor (PgR) is seen. Nuclear Topoisomerase staining is seen in scattered inflammatory cells.The features are of calcifying pseudotumour of the neuraxis (CAPNON).
DIAGNOSIS: 1-3: Craniocervical lesion: Calcifying pseudotumour of the neuraxis (CAPNON).
Case Discussion
Calcifying pseudo neoplasm of the neuraxis or CAPNON corresponds to a rare non-neoplastic non-inflammatory heavily calcified discrete intraparenchymal or extra-axial lesions of CNS.
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