UNRESECTABLE HIGH-GRADE NON-INTESTINAL-TYPE SINONASAL ADENOCARCINOMA: CASE REPORT AND REVIEW OF EMERGING SYSTEMIC THERAPIES

High-grade non-intestinal-type sinonasal adenocarcinoma (SNAC) is a rare and aggressive malignancy of the nasal cavity and paranasal sinuses. It typically presents with locally advanced disease and has a poor prognosis, with limited data guiding therapy. We describe a 70-year-old male who presented with progressive nasal obstruction and a right cervical lymph node mass. Imaging revealed an extensive sinonasal tumor with cervical nodal metastasis. Histopathological examination confirmed a high-grade non-intestinal-type adenocarcinoma lacking intestinal differentiation. Immunohistochemistry showed strong cytokeratin 7 positivity and absence of CDX2/CK20 staining, consistent with a non-intestinal phenotype; no salivary gland tumor markers were expressed. Given the advanced stage and unresectability, the patient received palliative systemic chemotherapy with weekly carboplatin and paclitaxel. Treatment was well tolerated, and after 8 weeks a partial clinical and radiologic response was achieved, with significant reduction of the tumor burden and improvement of symptoms. This case illustrates that platinum-taxane chemotherapy can induce meaningful tumor regression in high-grade sinonasal adenocarcinoma, suggesting a role for systemic therapy in metastatic or unresectable cases. We discuss the differential diagnosis (including intestinal-type adenocarcinoma and other sinonasal malignancies), the pathologic and molecular features (such as EGFR and TP53 mutations), and emerging treatment strategies for this rare tumor based on a review of the literature. Multimodal therapy and molecular profiling may improve outcomes in the future. This case underscores the importance of recognizing non-intestinal-type SNAC and the potential benefit of palliative chemotherapy in improving disease control and patient quality of life.