Calcifying pseudoneoplasms of the neuraxis (CAPNON): clinical features and therapeutic options

Calcifying pseudoneoplasms of the neuraxis (CAPNON) are rare, slow-growing lesions occurring anywhere in the central nervous system (CNS). Since their first description in 1978, only 39 cases have been reported in the literature.

The cases of two patients with histopathologically verified diagnoses of CAPNON are presented. Thereafter, we review all reports published so far with respect to study type, number of patients, anatomical area (intracranial, spinal, or both), clinical presentation, radiological presentation, therapy, duration of follow-up, incidence and type of complication, and outcome. Furthermore, current recommendations for the management of spinal and cerebral CAPNON are discussed.

A total of 19 retrospective articles were identified and selected for review: 6 case series (31.6 %) and 13 reports of single cases (68.4 %). The 19 articles and our two additional cases added up to a total of 19 patients with spinal CAPNON and 22 patients with intracranial CAPNON. All patients were treated surgically. A follow-up was provided in 13 patients with spinal (68.4 %) and in 16 patients with intracranial CAPNON (72.7 %), respectively. The follow-up showed no signs of recurrence in 12 of 13 patients with spinal CAPNON (92.3 %) and in 15 of 16 patients with intracranial CAPNON (93.7 %). One-tailed Fisher's exact test revealed no significant difference between complete and incomplete resection in terms of disease recurrence (spinal: p = 0.6842; intracranial: p = 0.3749). Analysis of the literature did not reveal any deaths directly associated with CAPNON.

Calcifying pseudoneoplasms are rare benign lesions of the CNS of yet unknown origin. Because of the increasing number of reports, this clinical entity should be taken into consideration in the differential diagnosis of intracranial and intraspinal calcified lesions.