Calcifying pseudoneoplasm of the neuraxis in direct continuity with a low-grade glioma: A case report and review of the literature.

Calcifying pseudoneoplasms of the neuraxis (CAPNON) are presumed to be a non-neoplastic reactive pathology, based on the frequent finding of granulomatous inflammation. To our knowledge, there are few reports of CAPNON in association with a neoplasm. Here, we report the case of a 62-year-old man presenting with headache, which was caused by CAPNON in the left cingulate gyrus. CT scan revealed a calcified mass exhibiting gradual growth and increasing peritumoral edema. MRI showed an intra-axial hypointense mass on T1- and T2-weighted images. Development of a peri-lesional hyperintense lesion on T2-weighted images suggested local edema or tumoral invasion. Gadolinium-enhanced T1-weighted images revealed mild peripheral enhancement of the calcified nodule. L-methyl-11 C methionine-positron emission tomography revealed the uptake of tracer in the calcified nodule. The calcified mass and its enveloping brain tissue were removed using a parietal craniotomy. The calcified tissue was surrounded by spindle-shaped cells positive for GFAP and nestin. The MIB-1 labeling index of spindle cells was around 10% (i.e. a hot spot). Fourteen months after surgery, gadolinium-enhanced MRI evidenced growth of a tiny residual lesion. Therefore, this report illustrates a potential case of CAPNON arising from low-grade glial neoplasm.