[Cancer associated retinopathy (CAR). Two clinical cases and review of the literature]

Abstract

The cancer associated retinopathy (CAR) is a paraneoplasic retinopathy in which an antigen-antibody reaction, due to retinal antigens, also expressed in tumours, leads to degeneration of retinal photoreceptor cells. We observed in CHL-Luxembourg, 2 clinical cases of non-Hodgkin's lymphoma with severe prognosis in whom we described the presence of anti-recoverin antibodies. The CAR is most frequently associated with small cell lung and ovarian carcinomas. Clinical symptoms (phosphenes, progressive loss of eyesight) sometimes, occur before the diagnostics of primary cancer. Retinal degeneration may be assessed by electroretinogram, visual field, fundus oculi. A crossed reactivity between tumour and retinal antigens may initiate an antigen-antibody reaction, that implicates optic lesions. Different antigenic proteins have been evidenced, the most frequent being the recoverin. This protein plays a role in the adaptation to light and darkness. It is expressed in more than 50% of different types of neoplastic cells and would play a role in tumour proliferation. The antigen-antibody reaction leads to death by apoptosis of photoreceptor and bipolar retinal cells. These antirecoverin antibodies are also observed in other retinal degenerative diseases. The diagnosis is confirmed by titration of antibodies in the serum by Western Blot, Elisa and immunohistochemical methods. However, this diagnosis is by exclusion (vs. brain metastasis, drug toxicity, demyelinating diseases, autoimmune non paraneoplastic retinopathies). Corticosteroids are the only therapy that can bring some benefit. There is no value in starting a therapy if the retinal degeneration has reached an advanced stage. Note that the CAR must be distinguished from the Melanoma Associated Retinopathy (MAR) which is a similar paraneoplastic syndrome, but with rapid evolution of its symptoms and different etio-pathogenesis.