Calcified Pseudoneoplasm of the Neuraxis

Abstract

Calcified pseudoneoplasms of the neuraxis are extremely rare non-neoplastic lesions that can exist anywhere in the CNS. Although benign, the lesions can cause substantial neurologic symptoms, typically related to mass effect on adjacent structures. Calcified pseudoneoplasms of the neuraxis can also mimic other entities such as calcified oligodendrogliomas and meningiomas. Nevertheless, the lesions can usually be strongly suggested at the time of imaging due to a number of fairly unique imaging characteristics. Here, the clinical presentation of a patient with a posterior fossa calcified pseudoneoplasm of the neuraxis is described, along with its imaging and pathologic features.

FIG 1.

Initial CT scan of the mass obtained 15 years before presentation at our institution. The images demonstrate a densely calcified mass in the right posterior fossa (asterisk), without substantial local mass effect.

FIG 2.

MR imaging at the time of presentation demonstrates a slight interval increase in the size of the mass. Dense intralesional calcifications are again observed, as evidenced by substantial signal drop-out on T2 (A) and susceptibility-weighted (B) images. Axial T1 image (C) shows areas of internal hyperintense signal. FLAIR image (D) shows adjacent vasogenic edema, with a mild associated mass effect on the fourth ventricle. Axial (E) and coronal (F) postcontrast images demonstrate intense peripheral enhancement around the perimeter of the lesion, as well as a possible dural tail (arrow).

FIG 3.

Histologic examination revealed a tumefactive lesion characterized by exuberant calcification (A, original magnification ×50) around areas of chondromyxoid fibrillary matrix (B, original magnification ×20). Palisading spindle cells and a mild chronic inflammatory infiltrate are present on the periphery (C, original magnification ×200). All specimens are stained with hematoxylin-eosin.