Specific retinal vasculitis in HLA-A29 birdshot retinochoroiditis, distinguishing it from other causes of vasculitis: A pilot study.

Abstract

Purpose: Human leukocyte antigen-A29 (HLA-A29) birdshot retinochoroiditis (BRC) is a noninfectious uveitis affecting independently the retina and the choroid. While the choroidal involvement is characterized by a stromal choroiditis, the retinal features of BRC were less well defined until a recent study determined a specific pattern of retinal involvement with seven features including profuse posterior retinal leakage, thick fluorescein angiography sheathing/staining, profuse disc hyperfluorescence, macular edema with foveal sparing, and circulatory arteriovenous pseudo delay. The aim of this study was to determine whether the specific pattern of retinal involvement was diagnostic for BRC distinguishing it from other causes of retinal vasculitis.

Methods: A retrospective comparative study comparing patients diagnosed with BRC to patients with other causes of retinal vasculitis. A score based on seven retinal features was calculated. The maximum possible score was 16. If the score reached ≥ 9, the vasculitis was considered to be compatible with BRC.

Results: Eighteen BRC and 18 non-BRC vasculitis were included in the study. The mean age of BRC patients was 49.5 ± 9.1 years, 11/18 females and 7/18 males (female 61%/male 39%). HLA-A29 antigen was present in all patients (100%). The mean age of patients in the control group with non-BRC vasculitis was 37 ± 17, 11/18 females and 7/18 males (female 61%/male 39%). The control group included nine cases of sarcoidosis chorioretinitis, six cases of intermediate uveitis of the pars planitis type, two cases of Behçet uveitis, and one case of tuberculosis chorioretinitis. The mean scores for the BRC group were 10.5 ± 1.7, while in the control group, it was 3.9 ± 2.8 (P < 0.0001, t-test). Using Fisher's exact test, the probability of the scores ≥ 9 to correspond to BRC was significantly different and higher than the scores of the group of non-BRC vasculitis (P < 0.0001). The positive predictive value was high amounting to 88.9%.

Conclusion: Retinal vasculitis related to BRC has specific findings leading, if present, to the diagnosis of BRC that should be ascertained by the search of indocyanine green angiography lesions with the ultimate confirmation by the presence of the HLA-A29 antigen.