Calcifying pseudoneoplasm of the neuraxis within the sellar region: illustrative case

BACKGROUND: There are numerous atypical lesions of the sellar and suprasellar region that are often mistaken for pituitary adenomas. It is important to consider rare mimics of more common pathologies in this region. OBSERVATIONS: The authors detail the case of a 37-year-old woman with hypopituitarism who was found to have an atypical sellar mass with slow growth on interval imaging. The lesion was debulked via a microscopic endonasal transsphenoidal approach and found to be a calcifying pseudoneoplasm of the neuraxis (CAPNON). LESSONS: CAPNON is a rare disease entity that may affect the sellar region. CAPNON should be on the differential diagnosis for sellar masses that are associated with T1 and T2 hypointensity on magnetic resonance imaging with minimal enhancement. Although CAPNON is not at risk for malignant progression, these benign lesions can continue to grow after a subtotal resection and require follow-up.