[Large cystic neurinoma: a case report]

Area of Science:

• Neurosurgery
• Neurology
• Oncology

Background:

• Acoustic neurinomas, also known as vestibular schwannomas, are benign tumors arising from the Schwann cells of the vestibulocochlear nerve (VIIIth cranial nerve).
• While typically solid, cystic variants can occur, presenting unique diagnostic and surgical challenges.
• Large cystic acoustic neurinomas are rare and can cause significant mass effect on surrounding structures in the cerebellopontine angle (CPA).

Observation:

• A 52-year-old male presented with progressive dysphagia, gait disturbance, and diplopia due to a large cystic acoustic neurinoma in the left cerebellopontine angle.
• Neurological examination revealed cranial nerve deficits (V, VII, IX, X, XII), nystagmus, and truncal ataxia.
• Radiological imaging, including CT and MRI, demonstrated a large cystic mass with rim enhancement, displacing the fourth ventricle and extending towards the foramen magnum.

Findings:

• Surgical excision via a left suboccipital approach revealed a cystic mass arising from the VIIIth nerve, compressing adjacent cranial nerves.
• Histological examination confirmed a benign acoustic neurinoma with extensive myxoid degeneration, necrosis, and abnormal vasculature within the cyst wall.
• These degenerative changes were identified as the primary cause of the extensive cystic formation.

Implications:

• This case highlights the importance of considering cystic acoustic neurinomas in the differential diagnosis of CPA masses, especially when presenting with atypical cystic features.
• Complete surgical resection is the primary treatment, though postoperative cranial nerve deficits can occur.
• Understanding the pathological basis of cystic formation aids in surgical planning and predicting potential complications.