Adenoid cystic carcinoma of the parotid gland presenting as temporal bone neoplasm: a case report

Problem: Temporal bone tumours are rare head and neck cancers that may involve both the parotid and the neck. In cases with concomitant temporal bone and parotid tissue involvement, tumour origin determination can be challenging. A tumour with parotid and temporal bone involvement is usually of temporal origin. The tumour may also be a rare parotid neoplasm with intratemporal invasion through the facial nerve, such as adenoid cystic carcinoma. These are slow-growing, yet locally aggressive tumours marked by late-stage distant metastases. Case report: We describe a case of parotid adenoid cystic carcinoma invading the temporal bone via the facial nerve, presenting as primary temporal bone tumour with parotid tissue involvement. We emphasize the significance of intracranial involvement by perineural invasion. Conclusion: Tumours mimicking temporal bone neoplasms can originate from the parotid tissue and invade through the facial nerve. Preoperative fine needle biopsy evaluation is indispensable for malignancy type determination and surgical planning.