Adenoid Cystic Carcinoma of the Maxillary Sinus with Isolated Trigeminal Anesthesia.

Adenoid cystic carcinoma (ACC) is a rare malignant secretory gland tumor. It is characterized by slow growth, long clinical course, local recurrences, and distant metastases. In the sinonasal tract, it most commonly arises in the maxillary sinus. It often presents at an advanced stage with perineural spread (PNS). Our patient presented with left-sided facial numbness without other symptoms. The numbness was localized to the left cheek, left side of nose, and left upper lip. Magnetic resonance imaging (MRI) of the brain revealed an enhancing lesion involving the left maxillary sinus with orbital invasion and posterior extension into the cavernous sinus. Transnasal endoscopic exploration with tissue removal revealed ACC. 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) scan revealed no evidence of distant metastases. Presentation of sinonasal ACC (SNACC) is variable depending on the involved structures. Characteristic PNS with ACC may cause neuropathic symptoms. This case displays a unique presentation of an advanced ACC of the maxillary sinus manifesting as isolated unilateral trigeminal anesthesia without sinonasal symptoms. The patient also failed to demonstrate any ocular or oculomotor symptoms despite extensive involvement of the orbit and surrounding structures. This case highlights the importance of recognizing ACC due to its association with late symptomatic manifestations. It also reinforces the need for clinical diligence with the workup of new onset neuropathic symptoms in the maxillary distribution of the trigeminal nerve.