Right CPA Epidermoid Cyst CaseNo: HN.1.1.1.1.001

Case Discussion CaseNo.HN.1.1.1.1.001

Axial T1 (Non-Contrast)

Axial T2

Axial T1 (Post contrast)

Sagittal T1 (Post contarst)

DWI

Clinical History : 15-year-old female presented with mild sensory changes on the right side of the face and intermittent dizziness.

Radiological Findings:  MRI: Right CPA lesion approximately 20 mm.

T1: Hypointense

Axial T1-weighted image showing a well-circumscribed, hypointense lesion in the right cerebellopontine angle, mildly compressing the brainstem

T2: Hyperintense

Axial T2-weighted image demonstrating a hyperintense lesion with characteristic 'cauliflower' like appearance and thin internal septations

Contrast-enhanced: No enhancement

Post-contrast axial T1-weighted image showing the non-enhancing nature of the lesion, distinguishing it from other CPA tumors

Post-contrast sagittal T1-weighted image illustrating the craniocaudal extent of the cyst and its relationship with adjacent neural structures.

DWI: Restricted diffusion

DWI provides the definitive diagnosis by showing hyperintensity, which is pathognomonic for epidermoid cysts compared to arachnoid cysts

Diagnosis: Epidermoid cyst (confirmed by pathological examination)

Teaching Points: 

• Epidermoid cysts contain keratin and slowly desquamating cellular debris; this dense, viscous content produces marked diffusion restriction on DWI.

  
  

• This feature is key in differentiating them from arachnoid cysts, which typically do not restrict diffusion.

  
  

• When combined with T1 hypointensity and T2 hyperintensity, diffusion restriction strongly suggests an epidermoid cyst even before pathology.

  
  

• Lack of contrast enhancement and slow growth further support the benign nature of the lesion and help us differentiate it from other lesions such as meningiomas and schwannomas.

  
  

• Surgical planning considers the lesion’s non-extension into the internal acoustic canal and relationship with neurovascular structures to minimize operative risk.

https://www.youtube.com/watch?v=93C0ohehwNo

Video Presentation : Epidermoid Cyst (Right CPA)

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