Skull Base Invasion Patterns and Survival Outcomes of Nonmelanoma Skin Cancers

Skull Base Invasion Patterns of Malignant Head and Neck Tumors: A Neurosurgical Perspective

Objective  Craniofacial resection (CFR) and temporal bone resection (TBR) on malignant head and neck tumors (MHNTs) invading skull base require accurate and precise determination of the tumor invasion. We investigated tumor skull base invasion patterns and surgical results in CFR and TBR cases. Methods  We performed either CFR or TBR for 75 selected patients with the possibility of en bloc resection over the period between 2011 and 2018. The medical charts of the selected patients were reviewed. Results  Primary tumor onset site (TOS) groups were: (1) nasal cavity/ethmoid sinus, 20 cases; (2) orbit, 10 cases; (3) maxillary sinus, 28 cases; and (4) external ear/temporomandibular joint, 17 cases. Grades for tumor invasion depth (TID) included: (I) extracranial invasion and skull base bone invasion; (II) extradural invasion; or (III) intradural invasion. Patients in groups 1 and 2 had a significantly higher frequency of grade II and III invasions than patients in groups 3 and 4. The main invasion site was nasal cavity superior wall and ethmoid sinus superior wall for group 1 tumors, orbit superior wall, and lateral skull base sphenoid bone for group 2 and 3 tumors, and lateral skull base temporal bone for group 4 tumors. Positive resection margins represented a significant negative prognostic factor. TID and TOS did not affect skull base margin status. Conclusion  Skull base invasion of MHNTs exhibits certain fixed patterns in sites susceptible to invasion based on the TOS. The frequencies of extradural and intradural invasions differed, indicating the importance for accurate preoperative tumor evaluation.

Elective Neck Dissection for Head and Neck Cutaneous Squamous Cell Carcinoma with Skull Base Invasion

Objectives Skull base invasion from cutaneous squamous cell carcinoma (cSCC) via perineural spread affects survival and the rate of regional metastasis. Our objective is to investigate the factors associated with elective neck dissection (END) in this population and the survival difference with END compared with observation for patients with a cN0 neck. Study Design Case series with chart review. Setting Academic. Subjects and Methods Patients were treated surgically for head and neck cSCC with skull base invasion via perineural spread with a cN0 neck from 2004 to 2014. Clinicopathologic data were collected and analyzed. Primary outcomes were disease-free survival (DFS) and overall survival (OS). Results Fifty-nine patients met inclusion criteria: 28 underwent an END and 31 underwent neck observation. Free tissue transfer reconstruction was significantly associated with END ( P < .001). Patients treated with an END had significantly improved 5-year DFS (57% and 32%, P = .042) and OS (60% and 37%, P = .036) compared with those who were observed and a significantly reduced rate of regional recurrence (9% and 37%, P = .024). The rate of occult nodal metastasis identified with END was 36% and is approximately equal to the regional failure rate of the neck observation group (37%). Conclusion END was more commonly used in cases requiring free tissue transfer. The use of END for head and neck cSCCs that have invaded the skull base is not routinely performed but was found to be associated with a survival advantage and reduced regional recurrence rate.