Diagnostic Dilemma: In a Case of Retro Clival- Prepontine and Anterior Cerebellar SOL and Review of Literature

Abstract

Abstract

Introduction / Background: Preoperative identification of lesion pathology is crucial for surgical planning and management. However, overlapping radiological features may lead to diagnostic uncertainty. We present a rare case of retro clival?prepontine and anterior cerebellar space-occupying lesions (SOLs), which mimicked two distinct entities radiologically but were proven histologically to represent a single pathology-an epidermoid cyst in different stages of evolution. Case Presentation: A 40-year-old woman presented with a three-month history of progressive headache, intermittent diplopia, facial numbness, and mild gait imbalance. Examination revealed left sixth nerve palsy, trigeminal hypoesthesia, and mild ataxia. Imaging showed two lesions: a hyperdense, non-enhancing midline prepontine mass without diffusion restriction, suggestive of a neuro-enteric cyst, and a left cerebellar lesion with restricted diffusion, consistent with an epidermoid cyst. Surgical excision via a left retro sigmoid suboccipital approach revealed both lesions interconnected by a thin arachnoid membrane. Histopathology confirmed keratinizing squamous epithelium with keratin flakes, diagnostic of an epidermoid cyst. Discussion: Intracranial epidermoid cysts are rare congenital lesions (0.2?1.8% of intracranial tumours) arising from ectodermal remnants during neural tube closure. They commonly appear hypodense on CT and show diffusion restriction on MRI. However, atypical ?white? epidermoid may be hyperdense on CT and hyperintense on T1 due to high protein, lipid, or haemorrhagic content. The coexistence of typical and atypical features in this case led to a diagnostic dilemma, initially suggesting two separate pathologies. Conclusion: This case underscores the radiological variability of epidermoid cysts and their potential to mimic other cystic lesions such as neuro-enteric or dermoid cysts. Awareness of atypical imaging patterns and consideration of evolving cyst content can help avoid misdiagnosis and guide appropriate surgical management.