Abstract

A 39-year-old man presented with a 9-year history of right-sided facial swelling due to adenoid cystic carcinoma of the right maxillary sinus, confirmed by biopsy in 2017 showing cribriform architecture, c-KIT positivity, HER2 negativity, and intermediate androgen receptor expression (7-8%). Initially declining surgery, he received imatinib (400mg daily, 2021-2023), achieving radiological stability (tumor 8.2 × 5.3 × 7.9cm to 7.7cm) without regression. Progression ensued with cavernous sinus invasion, internal carotid artery encasement (no occlusion), bilateral orbital apex involvement, optic neuropathy (right-eye blindness, ptosis), and skull base destruction, rendering the tumor unresectable. Bicalutamide (50mg daily, January 2024-October 2025; 26 months) induced initial partial response (slight size reduction, necrosis by June 2024) but failed to prevent marked progression by October 2025 (midline-crossing mass with bilateral ethmoid/orbital/sphenoid erosion). Therapy switched to Lenvatinib (January 2026), then Adriamycin-cyclophosphamide chemotherapy amid ongoing bilateral vision compromise and cranial neuropathies. This case illustrates sequential targeted attempts (c-KIT/AR inhibition) in AR-positive maxillary ACC with extreme perineural/skull base aggression, highlighting diagnostic/treatment challenges and need for novel trials.

Keywords:Adenoid cystic carcinoma; Salivary gland tumor; Cavernous sinus; Invasion; Diagnostic/treatment challenge

Abbreviations: ACC: Adenoid Cystic Carcinoma; MSGTs: Malignant Salivary Gland Tumors; TNM: Tumor, Nodes, and Metastasis; EMA: Epithelial Membrane Antigen; CD117: Cluster of Differentiation 117; p63: Tumor protein p63; ASMA: Alpha-Smooth Muscle Actin; CT: Computed Tomography; CE: Contrast-Enhanced; AR: Androgen Receptor; MSI: Microsatellite Instability; MMR: Mismatch Repair Proficient; R/M: Recurrent/Metastatic; SDCs: Salivary Duct Carcinomas; HER2: Human Epidermal Growth Factor Receptor 2; c-KIT: Cellular KIT Proto-oncogene; ADT: Androgen Deprivation Therapy; PIK3CA: Phosphatidylinositol-4,5-Bisphosphate3-Kinase Catalytic subunit Alpha; IHC: Immunohistochemistry