A Rare Presentation of Intracerebellar Schwannoma: A Case Report

Abstract

Background: Intracerebellar schwannoma is an extremely rare disease entity with only 21 case reports described in the literature. Case Description: A 68-year-old male presented with chronic headaches, dizziness, gait imbalance, and incoordination. Previous MRI had revealed a cystic lesion in the right cerebellum; however, patient was lost to follow-up. Updated MRI revealed dramatic enlargement of the lesion in addition to worsening clinical status. The patient underwent successful surgical resection. Conclusion: Intracerebellar schwannoma can be challenging to diagnose preoperatively due to its rare occurrence; however, it should be included in the differential diagnosis of cystic lesions in the cerebellum, and most cases can be successfully treated with complete surgical resection. Pathological examination revealed a spindle cell neoplasm with other typical histopathological features of schwannoma.

Keywords: intracerebellar cystic lesion; neurofibromatosis; schwannoma.

Figure 1

Right intracerebellar cystic lesion. (a) Axial noncontrast head CT shows a simple intra-axial cystic mass within the right cerebellum. The content is mildly heterogeneous. There is mild local mass effect effacing the fourth ventricle and causing slight tonsillar herniation with no vasogenic edema or obstructive hydrocephalus. (b) Axial T2-weighted image confirms the thin-walled cystic nature of the mass but also reveals a cyst-within-a-cyst element. (c) FLAIR demonstrates a hyperintense signal of the cyst-within-a-cyst which indicates slight complexity of the fluid content. (d) ADC MRI reveals no diffusion restriction of the fluid content which excludes epidermoid cyst. (e, f) T1 images lack susceptibility and hyperintense signal which rules out hemorrhage. (g, h, i) 3D T1-post gadolinium images reveal a small nodular component at the inferior aspect of the mass, associated with the cyst-within-a-cyst.

Figure 2

Case timeline.

Figure 3

Intracerebellar region tumor pathology. Microphotographs of the biopsied tissue shows spindled cell neoplasm with fascicular architecture and vague nuclear alignment (a, b) (H/E) focal degenerative atypia (b) (H/E). Reticulin showing extensive deposition around tumor cells characteristic of schwannomas. (c) Reticulin showing extensive deposition around tumor cells characteristic of schwannomas. Immunohistochemistry (d, e, f) showing the tumor to be strongly positive for S100 (d), SOX 10 transcription factor (nuclear (e)), and P16 (f). Immunohistochemistry (g, h) showing the tumor to have a well-defined border with adjacent cerebellar tissue (g) (GFAP) and focally positive for CD34 (h). Negative IHC included EMA, melanoma cocktail, inhibin, AE1/AE, keratin, and neurofilament.