Exploring the uncharted: adenoid cystic carcinoma nestled in temporal bone

Background Adenoid cystic carcinoma is an uncommon malignancy primarily arising from salivary glands. An extremely rare site for adenoid cystic carcinoma is the skull base. We report a case of adenoid cystic carcinoma of skull base who presented with common complaints of pain and right ear discharge. The discussion is made with emphasis on imaging evaluation simulating infective etiology with adjacent skull base osteomyelitis. Careful observation of the imaging findings and further evaluation of the patient revealed the neoplastic nature of the lesion with the final diagnosis being adenoid cystic carcinoma. Case presentation A 40-year-old female presented to our department with complaints of pain and right ear discharge since 6 months with progressive, extensive facial swelling and facial nerve palsy. The patient had undergone modified radical mastoidectomy thrice, but the details were not available. On imaging, there was a heterogenous extensive lesion extending from scalp till upper cervical region with extensive destruction of skull base and intra-cranial extension. The possibilities of temporal bone squamous cell carcinoma and extensive skull base osteomyelitis were considered. Further the biopsy of the lesion revealed adenoid cystic carcinoma. Conclusions Extensive lesions of the skull base can be of infective, neoplastic and inflammatory etiology. Distinguishing between these conditions is crucial, as they have similar imaging characteristics but require different management approaches. The presence of a lesion that displaces or destroys fascial planes, accompanied by solid mass-like enhancement, indicates a higher probability of a neoplastic origin rather than an infectious etiology. With squamous cell carcinoma being the most common neoplasm, adenoid cystic carcinoma of the skull base also needs to be understood due to its propensity for perineural spread and a high likelihood of recurrence.