Cerebellopontine angle pilocytic astrocytoma in adults: A systematic review

Abstract

Background: In adults, the cerebellopontine angle (CPA) pilocytic astrocytoma (PA) is very rare. This tumor has radiological features similar to those of a vestibular schwannoma in the few cases reported in the literature.

Methods: In this study, we conducted a systematic review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol and scrutinized all original studies pertaining to pontocerebellar angle PA in adult patients. We conducted an analysis of the clinical, radiological, and molecular components of all eligible articles. We have also reported a case involving a 67-year-old male individual in whom the PA exhibited radiological characteristics similar to an epidermoid cyst.

Results: After the screening phase, we found four cases of PA of the pontocerebellar angle. Three cases were identified that resembled vestibular schwannoma; however, in our case, the tumor resembled an epidermoid cyst. These uncommon tumors exhibit distinctive histological patterns and molecular characteristics (adenosine triphosphate dependent helicase (ATP- dependent helicase)+, Isocitrate dehydrogenase 1-), rendering them a potential differential diagnosis for glioblastoma (GBM).

Conclusion: The CPA PA has rarely been found in adult patients and should be considered in the differential diagnosis of vestibular schwannoma and epidermoid cysts. In these rare cases, the histological characteristics of PA are significant for the differential diagnosis of GBM.

Keywords: Cerebellopontine angle; Epidermoid cyst; Molecular markers; Pilocytic astrocytoma; Tumor.

Figure 1:

Flow diagram of systematic reviews of pilocytic astrocytoma in adults of the cerebellopontine angle.

Figure 2:

Magnetic resonance imaging (MRI) of pilocytic astrocytoma of cerebellopontine angle right in a 67-year-old man. (a) The T1-weighted axial MRI demonstrates a lesion of 4.5 × 1.7 cm maximum diameter, exhibiting a hypointense signal. (b) Gadolinium-enhanced T1-weighted axial MRI shows an extra-axial lesion with outfit and not homogeneous signal enhancement. This is mainly noticeable at the periphery of the lesion. (c) In the T2-weighted axial MRI, the lesion exhibits signal hyperintensities and appears to have an interface with nerve tissue. (d) In the T2 – fluid-attenuated inversion recovery-weighted axial MRI, the lesion shows signal hypertension and edema in the cerebellar parenchyma. (e) Diffusion-weighted imaging indicates a restricted diffusion of the lesion. (f) A postoperatively computed tomography scan revealed the presence of air bubbles at the lesion site and moderate edema of the cerebellar parenchyma.

Figure 3:

Histological examination of pilocytic astrocytoma of cerebellopontine angle right in a 67-year-old man. (a) HaematoxilinEosin (H&E) ×10 biphasic growth pattern characterized by compact areas alternating with microcystic areas, (b) H&E ×20 globuli ialini, (c) H&E ×40 granular body, (d) H&E ×20 microcystic areas, (e) H&E Rosenthal fibers, and (f) positive expression of the glial fibrillary acidic protein.