A 31-year-old woman presented with headaches, dizziness, tinnitus, and syncope. She also experienced difficulty swallowing and impaired balance and coordination. Imaging revealed a 4 mm mass lesion at the right aspect of the foramen magnum on computed tomography, and subsequent magnetic resonance imaging confirmed that extra-axial lesion (Figure 1). Surgical resection was performed, and histology confirmed the presence of a calcifying pseudoneoplasm of the neuraxis (CAPNON) (Figure 2). Following surgery, the patient’s condition improved, and she was discharged with recommendations for outpatient follow-up.
CAPNON is a benign, rare entity characterized by slow-growing non-neoplastic fibro-osseous lesions and is distinguished by the presence of calcium deposits within the tumor tissue.1, 2 The calcified material has a unique fibrillated quality at least focally and can become ossified. Reactive macrophages and inflammation are frequently present. The pathogenesis, clinical presentation, and outcomes are poorly understood.1 With only approximately 150 cases reported, diagnosis and management pose a challenge.2 CAPNONs frequently resemble meningiomas, cavernomas, chordomas, foreign body reactions, or low-grade astrocytomas.3, 4 CAPNONs located at the skull base may resemble intra-axial calcified lesions such as low-grade glial neoplasms (e.g., oligodendroglioma and ependymoma), mixed neuronal-glial tumors (e.g., ganglioglioma), vascular malformations (e.g., cavernous malformation), and granulomatous or infectious processes (e.g., tuberculosis).2
CAPNONs can occur at any location along the neuraxis and affect individuals aged 2-90 years, with a peak incidence between the age of 40 and 60 years.5 The most common presenting symptoms include headache and seizures, although some cases are discovered incidentally.3 Management depends on factors such as location, size, and presenting symptoms. Asymptomatic lesions may be monitored without intervention, whereas surgical resection is typically indicated for superficial lesions.3
Informed Consent: We obtained informed consent from the patient described in this report.
Authorship Contributions: Concept- M.S., O.L.A.N., B.A.P., M.L.D., L.F.F.; Design- M.S., O.L.A.N., B.A.P., M.L.D., L.F.F.; Supervision- M.S., O.L.A.N., B.A.P., M.L.D., L.F.F.; Fundings- M.S., O.L.A.N., B.A.P., M.L.D., L.F.F.; Materials- M.S., O.L.A.N., B.A.P., M.L.D., L.F.F.; Data Collection and/or Processing- M.S., O.L.A.N., B.A.P., M.L.D., L.F.F.; Analysis and/or Interpretation- M.S., O.L.A.N., B.A.P., M.L.D., L.F.F.; Literature Search- M.S., O.L.A.N., B.A.P., M.L.D., L.F.F.; Writing- M.S., O.L.A.N., B.A.P., M.L.D., L.F.F.; Critical Review- M.S., O.L.A.N., B.A.P., M.L.D., L.F.F.
Conflict of Interest: No conflict of interest was declared by the authors.