Malignant Transformation of Schneiderian Papilloma Presenting With Progressive Binocular Diplopia and Blepharoptosis.

Sinonasal tumors arising from Schneiderian papillomas, most frequently associated with squamous cell carcinoma (SCC), are rare and often present with non-specific symptoms, even in an advanced stage. Herein, we report the case of a 61-year-old male who presented with a four-month history of progressive binocular diplopia, blepharoptosis, and amblyopia, and upon the essential diagnostic work-up he was subsequently diagnosed with SCC arising from an SP. Surgical management was not warranted due to the extent of the disease, so induction chemotherapy with cisplatin and 5-fluorouracil (5-FU) was commenced, followed by definitive concurrent chemoradiotherapy (CRT). The patient was still alive at 25 months after his first presentation, receiving supportive care. Our case highlights the importance of early recognition of neuro-ophthalmological disorders related to sinonasal carcinomas, as diagnostic delay may lead to both functional complications and higher morbidity.