[Adenoid cystic carcinomas invading the skull base. Apropos of 4 cases and review of the literature].

Head and neck adenoid cystic carcinomas may invade the adjacent skull base by bone lysis and/or by perinervous and perivascular spread within the skull base foramina. Neurosurgical decision making is not well defined regarding the extent of intracranial tumor component removal, as neurosurgical expertise is limited for this peculiar type of tumors. The issue is to decide whether a radical supposedly locally curative surgery should be attempted, or if a large non disfigurating surgery is mandatory, keeping in mind the frequency of local recurrences and of distant metastases. Over a 13-year period, four adenoid cystic carcinomas invading the skull base were operated on at our institution: two tumors originated in the parotid gland, one in the sphenoid sinus, and one in the ethmoid sinus. Surgical removal was total in one case, subtotal in three cases. Post-operative irradiation was delivered in the four patients (two neutron irradiation, two conventional). One patient with advanced metastatic disease was submitted to chemotherapy. Three patients died from local tumor progression and distant metastases within three years after the intracranial tumor extension has been diagnosed. The patient with an ethmoid tumor is still alive seven years after surgery without any evidence of local tumor progression nor distant metastases. Surgery remains the gold standard treatment for adenoid cystic carcinomas invading the skull base. However, in our opinion a large tumor removal, without or with bone osteotomies, but without sacrifice of cranial nerves, cavernous sinus, internal carotid artery, and of the orbit allows patient survival with an acceptable comfort and absence of psychological distress due to disfigurating surgery nor surgically induced neurological functional deficit. Post-operative irradiation may sometimes stabilize locally the lesions. The place of chemotherapy has, yet, to be determined.