Primary Intracranial Cholesteatoma Presenting as a Cerebellar Mass Without Otologic Symptoms.

Intracranial cholesteatoma (epidermoid tumor) is an uncommon benign lesion that may demonstrate locally aggressive behavior, resulting in bone erosion and significant mass effect. Posterior fossa involvement presenting as a cerebellar syndrome in the absence of otologic symptoms is exceptionally rare and may closely mimic primary intracranial neoplasms, posing a diagnostic challenge. We report the case of a 29-year-old male who developed progressive vertigo, gait instability, and projectile vomiting one month after an appendectomy performed under spinal anesthesia. Neurological examination revealed mixed vertical and horizontal spontaneous nystagmus, limb dysmetria, and truncal ataxia. MRI showed a large posterior fossa lesion with marked diffusion restriction, absence of contrast enhancement, and extension into the cerebellopontine angle and upper cervical canal. The patient underwent suboccipital craniectomy with microsurgical excision of the lesion. Intraoperatively, a well-circumscribed, pearly white, encapsulated lesion containing keratinous material was identified. Histopathological examination confirmed the diagnosis of cholesteatoma. Postoperatively, the patient experienced progressive resolution of neurological symptoms, and a follow-up MRI at six months demonstrated no evidence of recurrence. This case emphasizes that intracranial cholesteatoma with posterior fossa extension should be included in the differential diagnosis of cerebellar masses, even in the absence of otologic symptoms. Diffusion-weighted MRI is essential for accurate diagnosis, and early complete surgical excision is associated with an excellent prognosis.