Intracerebral Calcifying Pseudoneoplasm of the Neuroaxis (CAPNON) Presenting with an Atypical Immunohistochemical Profile: Case Report and Review of the Literature

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.

The Ascension of Ronald Tasker to the Constellation of Stereotactic and Functional Neurosurgery Icons: December 18, 1927–April 19, 2023

“…Ron was a renowned and active “layman” bird watcher in Canada. Accordingly, he was a member of the Board of Directors (1975–1980, 1982–1990, and 1991–1995) and Chairman (1978–1980, 1983–1987, and 1988–1996) of the Long Point Bird Observatory – Birds Canada; a member of the Executive Board of Directors of the Federation of Ontario Naturalists (1982–1984); and Trustee of The Nature Conservancy of Canada (1987 and 1994) [2]. In 1991, he authored, with Holmes, Hess, and Hanks, The Ontario Butterfly Atlas [3].…”

“…Upon completing his neurosurgical training, Ron made a pilgrimage to Madison, Wisconsin, as a postdoctoral McLaughlin Traveling Fellow to work with the preeminent neurophysiologist Clinton Woolsey, who, to use Ron’s words, taught him to think about the nervous system in an organized fashion. Following his time in Wisconsin, Ron traveled to major functional neurosurgery centers in Paris, Stockholm, and Freiburg, to train with Tailarach, Guiot, Leksell, and Hassler (1959–1961) [1, 2, 4].…”

“…Ron taught in the Faculty of Medicine at UofT for over 40 years. He was a very active member of the Graduate Faculty of Medical Science, School of Graduate Studies, and the Playfair Neuroscience Institute from 1978 to 1999, when he became an Emeritus Member [1, 2, 4].…”

“…Ron continued his superb work in functional neurosurgery as a senior neurosurgeon at TWH until his retirement in 1998, when he was appointed as honorary staff (shown in Fig. 3) [2, 4]. In the same year, Ron’s wife Mary organized a stereotactic conference in Pond Inlet, Baffin Island, in the Canadian Arctic, to celebrate Ron’s retirement [5].…”

“…In the same year, Ron’s wife Mary organized a stereotactic conference in Pond Inlet, Baffin Island, in the Canadian Arctic, to celebrate Ron’s retirement [5]. Ron continued to go to his office following his retirement, once a week on Wednesdays, to see some of his patients who simply refused to see any other doctor [2]. In August 2023, a group of functional neurosurgeons convened in Ilulissat, Greenland, for the most recent Arctic meeting, where Ron’s legacy was once again celebrated [5].…”