Variations of en Bloc Resection for Advanced External Auditory Canal Squamous Cell Carcinoma: Detailed Anatomical Considerations

Simple Summary From the viewpoint of surgical anatomy, surgical patterns of temporal bone cutting to achieve negative margin resection for advanced squamous cell carcinoma of the external auditory canal can be divided into four categories: conventional lateral temporal bone resection (LTBR), extended LTBR, conventional subtotal temporal bone resection (STBR), and modified STBR. Extended LTBR is divided into four types: superior, inferior, anterior, and posterior procedures. Several directional extension procedures can be combined based on the extension of the tumor to achieve negative margin resection. Furthermore, en bloc resection with the temporomandibular joint or glenoid fossa increases the technical difficulty of a surgical procedure because the exposure and manipulation of the petrous segment of the internal carotid artery are limited from the middle cranial fossa. Accurate preoperative evaluation of the tumor extension and preoperative consideration of the exact resection line are required to achieve negative margin resection. Currently, only lateral temporal bone resection (LTBR) and subtotal temporal bone resection (STBR) are widely utilized for the surgical treatment of advanced squamous cell carcinoma of the external auditory canal (EAC-SCC). However, there are few descriptions of variations on these surgical approaches. This study aimed to elucidate the variations of en bloc resection for advanced EAC-SCC. We dissected the four sides of cadaveric heads to reveal the anatomical structures related to temporal bone resection. From the viewpoint of surgical anatomy, surgical patterns of temporal bone cutting can be divided into four categories: conventional LTBR, extended LTBR, conventional STBR, and modified STBR. Extended LTBR is divided into four types: superior, inferior, anterior, and posterior extensions. Several extension procedures can be combined based on the extension of the tumor. Furthermore, en bloc resection with the temporomandibular joint or glenoid fossa increases the technical difficulty of a surgical procedure because the exposure and manipulation of the petrous segment of the internal carotid artery are limited from the middle cranial fossa. Surgical approaches for advanced SCC of the temporal bone are diverse. They require accurate preoperative evaluation of the tumor extension and preoperative consideration of the exact line of resection to achieve marginal negative resection.