Supplementary Material for: Adenoid Cystic Carcinoma of the Sinonasal Cavity: a case report and literature review

Intrudoction: Adenoid cystic carcinoma (ACC), a rare, aggressive malignancy of secretory epithelia, often presents with nonspecific symptoms, delaying diagnosis. Case presentation: A 67-year-old male reported 10 months of nasal obstruction, mouth breathing, and sleep disturbances. Initial evaluation for foreign body obstruction revealed septal deviation and sinonasal low-density tissue on CT. MRI identified a 7×4.5×7 cm heterogeneous lesion invading nasal structures, paranasal sinuses, and nasopharynx with diffusion restriction. Tru-cut biopsy confirmed ACC via cribriform, tubular, and solid basaloid cell patterns, pseudocystic spaces, biphasic ductal-myoepithelial cells, and perineural invasion. Immunohistochemistry (CK7, CD117, p63, S100) supported the diagnosis, with tumor-free margins and no metastases. Multimodal therapy (30 VMAT sessions, 4 cisplatin-vinorelbine cycles) improved symptoms. Conclusion: This case illustrates ACC’s diagnostic complexity, requiring advanced imaging and histopathology to exclude mimics. Despite indolent early progression, ACC’s neurotropic spread and late-stage detection demand aggressive treatment. While surgery with adjuvant radiotherapy remains standard, the absence of metastases here underscores its variable behavior.