Focally deficient bilateral lateral mastoid walls: an unusual anatomical variation-a case report

The temporal bone represents the most intricate bony structure within the human body, which consequently renders its radiological assessment similarly complex. Advances in imaging technology provide enhanced insight into the anatomy of the temporal bone, alongside an understanding of the structural variations that may resemble pathological conditions.

This report presents the case of a 33-year-old male patient who exhibited symptoms consistent with right-sided chronic suppurative otitis media (CSOM) persisting for two years. In addition to demonstrating the characteristic high-resolution computed tomographic (HRCT) imaging features associated with CSOM, the patient displayed an unusual anatomical variant characterized by a focally deficient lateral wall of the mastoid process in the region of McEwen triangle on both sides, with a large adjacent air cell on the medial aspect. In the absence of any adjacent contiguous pathological changes on imaging and no prior surgical intervention, the focal wall defects were considered a congenital anomaly, obviating the need for any additional confirmatory method. The patient underwent a canal wall down mastoidectomy for right CSOM. A prior knowledge of such a congenital anomaly cautioned the operating surgeon to prevent inadvertent injury to the dural plate or lateral semicircular canal during drilling the bone through McEwen triangle while performing mastoidectomy.

A thorough preoperative workup is imperative to mitigate the risk of unforeseen surgical complications as seen in the present case. The anatomical variant described in the reported case has not been documented in the existing medical literature to date and certainly has significant clinical and surgical implications for patient management.