Helioenai  S. Alencar,Victor  P. Coelho,Luiz A.  Ferreira-Filho,Lissa  C. Goulart,Siderley  S. Carneiro,Osvaldo  Vilela-Filho,
Intracerebral Calcifying Pseudoneoplasm of the Neuroaxis (CAPNON) Presenting with an Atypical Immunohistochemical Profile: Case Report and Review of the Literature
Surgical Case Reports
2020
2613-5965
http://dx.doi.org/10.31487/j.SCR.2020.12.18
https://www.sciencerepository.org/intracerebral-calcifying-pseudoneoplasm-of-the-neuroaxis-capnon-presenting_SCR-2020-12-118 
Abstract: Background: Calcifying pseudoneoplasm of the neuroaxis (CAPNON) is a very rare benign lesion that can
be located anywhere in the nervous system, with only 59 intracranial cases described. The general lack of
knowledge about this lesion hinders its preoperative diagnosis. Despite the consistent image findings, the
final diagnosis is only established based on anatomopathological and immunohistochemical studies. The
lesion is more commonly positive for epithelial membrane antigen (EMA) and vimentin, and negative for
glial fibrillary acidic protein (GFAP) and S-100, suggesting a leptomeningeal origin. The opposite, however,
may also occur, although very rarely (just two cases positive for GFAP and negative for EMA and vimentin
reported this far). The treatment consists of total resection of the lesion, which yields a good prognosis.
Case Presentation: We report the case of a 23-year-old female who presented with disperceptive focal
seizures, sometimes evolving to bilateral tonic-clonic seizures, starting at age 9. She had a nodular calcified
lesion in the left precuneus and inferior parietal lobe. The lesion was completely resected, and the
immunohistochemical study revealed positivity for EMA, vimentin, GFAP, and S-100. No case hitherto
published was positive for all four markers. This atypical immunohistochemical profile of the CAPNON
may suggest a dual origin of this lesion, both parenchymal and leptomeningeal.
Conclusion: The general lack of knowledge of CAPNON makes this lesion underdiagnosed. Therefore, in
the face of a calcified lesion in the nervous system, one should consider the possibility of a CAPNON among
the differential diagnoses. The immunohistochemistry is undoubtedly an important tool, but the
anatomopathological study, associated with image findings, remain the gold standard for the diagnosis of
CAPNON.Keywords:  CAPNON, calcifying pseudoneoplasm of the neuroaxis, intracerebral calcification, epilepsy, GFAP, S-100, EMA, vimentin