Stage III small cell lung cancer with paraneoplastic optic disc swelling

What happened, in summary

This 77-year-old man came to medical attention through an eye clinic rather than through lung symptoms. Bilateral optic disc swelling was found incidentally during cataract review, and his vision was initially preserved. Early testing, including brain and orbital imaging, lumbar puncture, temporal artery ultrasound, and broad serologic evaluation, did not identify a clear cause. Six weeks later, the disc swelling persisted and he developed blurred vision with early visual-field defects. He was started on oral prednisolone 40 mg daily for 2 weeks, followed by a gradual taper. Further testing then showed paraneoplastic antibodies, anti-CV2/CRMP-5 and anti-Hu. PET-CT identified a metabolically active right hilar/right upper-lobe endobronchial nodule that had grown from 9 x 5 mm to 19 x 16 mm. Endobronchial ultrasound-guided biopsy confirmed small cell lung cancer, graded as T1cN1M0. He received carboplatin plus etoposide chemotherapy, followed by sequential radical radiotherapy to 40 Gy in 15 fractions. The steroid course improved the eye findings before cancer treatment was completed. Three months after steroid initiation, the optic disc swelling had fully resolved, visual acuity was 6/7.5 in both eyes, color vision was preserved, and he reported no subjective worsening. Eighteen months after the lung cancer diagnosis, there was no evidence of recurrence. His outcome combined cancer control with recovery from a potentially vision-threatening paraneoplastic eye complication. Before the diagnosis, his visual acuity had fallen from 6/12 to 6/18 with glasses, while pinhole acuity remained 6/9, making early treatment important for preserving function and daily independence.