Extra axial medulloblastoma of the cerebellopontine angle: A rare case report

Abstract

Medulloblastoma is the most frequent malignant brain tumor in children. Originating in the cerebellum, they are typically intra-axial tumors. In adults, they represent less than 1% of brain tumors. However, the occurrence of extra-axial medulloblastoma is possible but extremely rare, and slightly more frequent in the adult population. We present a rare case of extra-axial medulloblastoma, diagnosed in a 22-year-old male, through advanced imaging techniques, followed by confirmation through anatomopathological examination. This case calls attention to the necessity of knowledge of the various diagnostic possibilities when interpreting radiological images, leading to enhanced patient care and furthering our understanding of these exceptional entities.

Keywords: Cerebello-pontine angle; Extra axial; Histopathology; MRI; Medulloblastoma; Schwannoma.

Fig. 1

Precontrast CT scan reveals the presence of an expansive solid mass of the posterior cerebral fossa (blue arrow) with mass effect on the fourth ventricle (yellow arrow) (A). Trans ependymal resorption (white arrow) (B).

Fig. 2

Hypo intense signal on T1 (A) (yellow arrow), iso signal on FLAIR (B) (blue arrow) and a thin layer of CSF surrounding tumor on T2 (red arrow).

Fig. 3

Hypersignal on diffusion-weighted imaging (A), low ADC value (B) (red arrows), homogeneous enhancement (C) (stars).

Fig. 4

vasogenic oedema adjacent to the tumor (A), and on periventricular (B) (green arrows).

Fig. 5

(A) Sagittal, (B) Coronal: herniation of the right cerebellar tonsil (blue arrows).

Fig. 6

(A) Sagittal, (B) Axial: multiple extramedullary nodular lesions (blue arrows).