Choroidal neovascularization associated with cancer-associated retinopathy

Purpose: To report an unusual association between cancer-associated retinopathy (CAR) associated with invasive thymoma and choriodal neovascularization (CNV), treated by photodynamic theraphy (PDT). Methods: A 39-year-old man affected with thymoma and paraneoplastic syndrome (myasthenia gravis and diarrhoea) was observed between October 1997 and September 2007. The patient developed progressive visual dysfunction including bilateral visual acuity loss and concentric constriction of visual fields. Ophthalmological, immunological and systemic examinations were performed. Immunological evaluations included an assessment of antibody activity by indirect immunohistochemistry on sectioned rhesus monkey eye, and Western blot reactions upon an extract of pig retina. Results: Fundus ophthalmoscopy and fluorescein angiography revealed retinal vessel attenuation and retinal pigment epithelium degeneration. Electroretinogram suggested both rod and cone dysfunction. Indirect immunohistochemistry identified antibody activity within the photoreceptor outer segments. Western blots on the retina revealed that most of the patient's antibody activity was focused upon a retinal protein antigen approximating 145 kD. These findings share the commonalities of size and retinal distribution of the interphotoreceptor retinoid-binding protein (IRBP), a recognized autoantigen. The surgically resected mediastinal tumour was diagnosed as invasive thymoma. No other malignancy has since been found throughout nearly 10 years of follow-up. In March 2006, the patient developed a subfoveal CNV in his left eye, which was treated by PDT. Conclusion: We describe the third case of paraneoplastic retinopathy associated with invasive thymoma. This is the first example of CAR involving autoantibodies reactive with a retinal protein having the characteristics of the IRBP, and is also the first complicated by CNV treated by PDT.