Calcifying pseudoneoplasm of the neuraxis (CAPNON): Unraveling a rare non-neoplastic calcified central nervous system lesion

INTRODUCTION AND IMPORTANCE: Calcifying pseudoneoplasms of the neuraxis (CAPNON) are infrequent benign brain tumors. They demonstrate slow growth and are characterized by calcium deposits within the tumor tissue. CAPNONs are observed in the supratentorial compartment of the brain. Due to their rarity, increasing knowledge of CAPNONs is essential for accurate diagnosis and effective management of affected patients. This report describes a case of CAPNON diagnosed in a 56-year-old female and discusses the clinical, imaging, and histopathological findings of this rare entity. CASE PRESENTATION: A 56-year-old female presented with a history of recurrent holocranial headache and dizziness, progressively worsening over the last month. Physical and neurological examinations revealed no evident abnormalities. Brain magnetic resonance imaging revealed a calcified and cystic mass, measuring 40 × 32 mm in the right frontal lobe. Complete excision of the mass was done. Histologically, the lesion was composed of glial tissue with abundant amorphous lamellar calcification and a myxoid matrix in the background. Concentric circular calcifications were observed with osseous metaplasia present in some areas. Palisading spindle to epithelioid cells was noted around the lesion. The final diagnosis was CAPNON. The postoperative course was uneventful, and one year of follow-up revealed no signs of recurrence. DISCUSSION: CAPNON typically occurs in middle-aged adults and can present with variable symptoms depending on its location within the brain, including seizures, headaches, or neurological deficits. Surgical resection is considered the optimal treatment for CAPNON. Raising awareness and understanding of this rare entity is necessary for accurate diagnosis and management of patients affected by this condition.