Calcifying pseudoneoplasms of the neuraxis (CAPNON). A case report

Abstract

Calcifying pseudoneoplasms of the neuraxis (CAPNON) are rare, slow-growing, benign lesions occurring throughout the neuroaxis that are frequently misdiagnosed and overlooked by clinicians. Here, we report a case of a 56-year-old woman who presented with a history of recurrent headache for the previous six years. Magnetic resonance imaging (MRI) revealed a 2.3-cm-sized solid mass in the right frontal lobe that was surrounded by marked edematous areas. The lesion demonstrated dense calcification and avid enhancement. The lesion was initially diagnosed as oligodendroglioma, and then found to be CAPNON based on histopathology of a surgically resected tissue. Genetic analysis revealed a nonsense mutation in the CUL4B gene. The patient's condition appeared to reflect a reactive, rather than neoplastic, process. Clinicians should be prepared to detect such pseudotumors histopathologically in order to avoid unnecessary differential tests of neoplastic or infectious diseases, as well as potentially harmful therapies.

Calcifying pseudoneoplasms of the neuraxis (CAPNON): The great tumor mimicker

“…CAPNONs are rare lesions of the CNS affecting both children and adults with a modest male predominance [1] . They are slow-growing benign lesions presumably attributable to a reactive proliferative process induced by various trigger factors, such as infection, inflammation and injury, and may be possibly associated with inflammatory, degenerative, vascular and neoplastic diseases [2] , [3] , [4] . However, its underlying etiology is still non completely defined and other explanations have been proposed too, including neoplastic process [5] , immune-mediated process [6] , tissue calcinosis [7] , and less likely, metaplastic transformation [8] .…”

Meningioangiomatosis Combined with Calcifying Pseudoneoplasms of Neuraxis

“…Later, the brain lesion was named ”meningioangiomatosis” by Worster-Drought et al in 1937 [ 3 ]. Calcifying pseudoneoplasms of the neuraxis (CAPNON) are rare, slow-growing, benign tumor-like lesions that can occur anywhere along the neuraxis, including the brain and spine [ 4 , 5 ]. Originally described by Rhodes and Davis in 1978, CAPNON is also called fibro-osseous lesions [ 6 ].…”

18F-FET PET/CT in Calcifying Pseudoneoplasm of the Neuraxis

“…3,4 Usually considered benign and noninvasive lesions, their prognosis is usually favorable after total surgical excision. 4 Despite its rarity, CAPNON should be included in differential diagnosis of tumor-like masses as a calcified meningioma, glial tumors, cavernous malformations, chondroma, chondrosarcoma, schwannoma, granulomatous lesions, inflammatory lesions, neurofibroma, calcifying tuberculosis, calcified synovial cyst, and chronic epidural abscess. 5-7 18 F-FET PET/CT, a PET radiotracer of amino acid uptake, may be useful in the differential diagnosis between neoplastic brain tumors and nonneoplastic lesions and grading of glial tumors.…”

“…Although often asymptomatic, clinical manifestation is variable and dependent on location and size. Indeed, mass effects can determine local compression and irritation of contiguous nervous tissue, resulting in headache, seizures, and cranial neuropathy 3,4 . Usually considered benign and noninvasive lesions, their prognosis is usually favorable after total surgical excision 4 .…”

“…Indeed, mass effects can determine local compression and irritation of contiguous nervous tissue, resulting in headache, seizures, and cranial neuropathy 3,4 . Usually considered benign and noninvasive lesions, their prognosis is usually favorable after total surgical excision 4 . Despite its rarity, CAPNON should be included in differential diagnosis of tumor-like masses as a calcified meningioma, glial tumors, cavernous malformations, chondroma, chondrosarcoma, schwannoma, granulomatous lesions, inflammatory lesions, neurofibroma, calcifying tuberculosis, calcified synovial cyst, and chronic epidural abscess 5–7 .…”