BACKGROUND: Acinic cell carcinomas (AcCCs), rare malignancies of the salivary glands, often recur and metastasize, particularly in the skull base. Conventional radical resection can be invasive for skull base AcCCs adjacent to cranial nerves and major vasculature, and the effectiveness of stereotactic radiosurgery (SRS) as an alternative is not well established.
METHODS: This case report details the application of SRS for recurrent skull base AcCCs. A 71-year-old male with a history of resection for a right mandibular AcCC 23 years earlier experienced tumor recurrence involving the right cavernous sinus and nasal cavity. He underwent endoscopic transnasal surgery followed by SRS targeting different tumor locations-the cavernous sinus to the pterygopalatine fossa, maxillary sinus, and clivus-each with a prescribed dose of 20 Gy to the 40% to 50% isodose line. After the first skull base metastasis, additional sessions of localized SRS after endoscopic surgery led to a 12-year survival without sequela.
CONCLUSIONS: This is a report indicating that SRS for skull base AcCCs can achieve favorable local control, functional preservation, and long-term survival. SRS may be suitable for skull base AcCC given the lesion\'s tendency toward multiple local recurrences. Further investigation is needed to validate the treatment\'s efficacy.

BACKGROUND: Polymorphous adenocarcinomas (PACs) are rare tumors arising from the salivary glands. Radical resection and postoperative radiotherapy are the mainstays of treatment. However, complete tumor resection is not always achievable when the tumor invades the skull base. Stereotactic radiosurgery (SRS) could be a less invasive alternative for treating skull base PACs.
METHODS: A 70-year-old male with a history of surgery for a right palatine PAC presented with right visual impairment, diplopia, and ptosis. Imaging studies revealed tumor recurrence invading the right cavernous sinus (CS). SRS using a gamma knife was performed for this recurrence, prescribing a marginal dose of 18 Gy at a 50% isodose line. Five months after SRS, his symptoms were relieved, and the tumor was well-controlled for 55 months without any adverse events.
CONCLUSIONS: To the best of the authors\' knowledge, this is the world\'s first case of recurrent skull base PAC invading the CS that was successfully treated with salvage SRS. Thus, SRS may be an applicable treatment option for skull base PACs.

UNASSIGNED: To investigate the clinical performance, pathological characteristics, treatment and prognosis of salivary gland malignant tumor (SGMT) with skull base metastasis.
UNASSIGNED: Five SGMT patients with skull base metastasis were retrospectively studied. Major clinical symptoms included headache, facial paralysis, and ear hearing loss. Three patients had previous history of SGMT resection. All patients underwent preoperative computed tomography (CT) and magnetic resonance imaging (MRI). Craniotomy was performed in three patients, and all the five patients underwent radiotherapy and chemotherapy.
UNASSIGNED: Two patients were confirmed as having adenocarcinoma, one patient was pathologically confirmed to have squamous cell carcinoma, one patient had ductal carcinoma, and one patient had acinar cell carcinoma. One patient died after 2 years of treatment, and the remaining 4 patients were followed up for 6 ∼ 24 months, suggesting that the tumor size was not enlarged or showed no local recurrence.
UNASSIGNED: SGMT with skull base metastasis is extremely rare, and due to similar imaging characteristics, it can be easily misdiagnosed as meningioma or schwannoma. Early diagnosis, extent of invasion, surgery and combination of chemotherapy and radiotherapy are the prognostic factors of the disease.