A 47-year-old man noticed quite suddenly visual loss, photopsia and night blindness in August 2003. When he visited our hospital in October 2003, his visual acuity was counting fingers bilaterally, and slit-lamp test revealed normal anterior segments. Funduscopic examination revealed narrowing of the retinal arteries and slight atrophy of retinal pigment epithelium (). Goldmann perimetry showed only peripheral islands of vision, and the standard full-field 20 J single flash electroretinogram (ERG) was non-recordable (). Chest x-ray, chest CT scanning () and chest MRI () revealed the presence of thymoma, but no other malignancy was found by positron emission tomography scanning. From the serum sample collected at the initial presentation, antirecoverin antibodies were detected by western blotting. The patient received systemic corticosteroid treatment, 1000 mg of methylprednisolone for 3 days, but his vision did not improve. He underwent thymectomy in November 2003, and the encapsulated tumour was removed (). Histopathological diagnosis was non-invasive cortical thymoma. He lost light perception 4 months after the onset.
Figure 1 Clinical features of a 47-year-old male patient with progressive visual loss. (A) Fundus image of the right eye showing narrowing of retinal arteries and retinal pigment epithelium atrophy. (B) Standard full-field 20 J single flash electroretinogram (ERG) (more ...)
Three years after tumour resection, the patient's serum was again tested for the presence of antiretinal autoantibodies by ELISA using sera from a known antirecoverin CAR patient as a positive control or from a healthy donor as a negative control, and a high titre of antirecoverin autoantibodies was still present (). Immunohistochemistry performed on paraffin-embedded sections of the resected tumour revealed a strong staining with serum from another patient with CAR containing antirecoverin antibodies but not with serum from a healthy donor, suggesting the presence of recoverin protein in the thymoma cells (). It is therefore assumed that antirecoverin antibodies were initially elucidated against recoverin present in thymoma cells and are now reacting with recoverin present in the retina.
Figure 2 (A) ELISA of antirecoverin antibodies in the serum. Serum from the patient contains a high titre of antirecoverin antibodies (Abs). Serum from a known CAR patient containing antirecoverin antibody is also tested as a positive control. (B) Immunostaining (more ...)