DOI: https://doi.org/10.36347/sjmcr.2026.v14i11.015

Pages: 2465-2469

Introduction: Nasopharyngeal carcinoma can remain clinically silent until it extends to adjacent structures, including the skull base and cavernous sinus. In some cases, ophthalmological symptoms may be the first indication of an underlying malignancy. Case presentation: We report the case of a 47-year-old patient with no significant medical history who presented with sudden-onset binocular diplopia that had persisted for one month, accompanied by weight loss and asthenia. Ophthalmological examination revealed esotropia and limitation of right-eye abduction, with preserved visual acuity and no optic disc abnormalities. Lancaster testing confirmed right sixth cranial nerve palsy. Given the associated general symptoms, further investigations were performed. MRI revealed a nasopharyngeal mass measuring 42 × 26 × 29 mm, extending to the skull base and right cavernous sinus and involving the intracavernous internal carotid artery. Histopathological examination confirmed undifferentiated nasopharyngeal carcinoma. No distant metastases were identified, and the disease was classified as T4N2M0. The patient received three cycles of induction chemotherapy. As subsequent assessment showed stable disease, concurrent chemoradiotherapy was planned. A follow-up Lancaster test was performed three months after treatment. Conclusion: This case illustrates how acute binocular diplopia may reveal an advanced nasopharyngeal carcinoma, even in the absence of typical nasal or otological symptoms. Careful ophthalmological examination, followed by appropriate neuroimaging, can play a decisive role in identifying the underlying cause and facilitating timely multidisciplinary management.