A 71-year-old woman presented with a 6-week history of occipital headache and unsteadiness. Contrast-enhanced computed tomography and magnetic resonance imaging studies revealed a solitary large posterior fossa tumor in the left cerebellopontine angle measuring 47 × 43 × 45 mm. The tumor resulted in moderate hydrocephalus and significant mass effect with compression of the pons and medulla. She underwent a stereotactic right ventriculoperitoneal shunt insertion followed by a stereotactic craniotomy and complete excision of the tumor. The operation went uneventfully, and the patient had an uncomplicated recovery. Histopathologic examination revealed a benign pleomorphic adenoma (benign salivary gland tumor) with a classic appearance comprising an admixture of ductal epithelial cells, myoepithelial elements, and nodules of myxochondroid stroma. No extracranial source has been identified despite extensive investigation and 8 years of follow-up.
This case study illustrates a classic primary central nervous system pleomorphic adenoma in an unusual intracranial site. Its pathogenesis is postulated to involve salivary gland heterotopia.