Frosted branch angiitis in an octogenarian with infective endocarditis

To present the difficulties in diagnosing frosted branch angiitis (FBA) in an elderly person, and to present the likely immunogenic association of FBA with alpha-hemolytic streptococci.

Thorough review of the medical records of an 80-year-old white man diagnosed with FBA. Patient consent was obtained before the writing of this article.

Our patient presented with 1 week of decreasing vision and floaters in his right eye and 3 days of floaters in his left eye. Significant medical history included a prosthetic mitral valve. Notable features on examination were bilateral retinal vascular sheathing, with retinal edema and hemorrhage. Preliminary investigations-including a transoesophageal echocardiogram-did not reveal intraocular or systemic infection, autoimmune disease, or underlying malignancy. Idiopathic FBA was unlikely given that the majority of cases had been documented in middle-aged Japanese populations. Thus, we chose to treat our patient empirically for common causes of retinal vasculitis such as viral retinitis. Interestingly, 2 weeks after the diagnosis of FBA, our patient became febrile. He was subsequently diagnosed with infective endocarditis and commenced on intravenous vancomycin (penicillin allergy). Review of his transoesophageal echocardiogram found an oscillating lesion that had been initially missed. Therefore, it is likely that our patient had blood culture-negative endocarditis at the time of presentation. This was further supported by the regression of his ocular disease with intravenous vancomycin.

We hypothesize that our patient developed FBA as an immunogenic response to Streptococcus viridans and Streptococcus oralis infection. Previous associations between streptococci and FBA have been made. Notably, beta-hemolytic streptococcal antigens are known to cross-react with retinal antigens. However, the implicated pathogens in our patient were alpha-hemolytic. Alpha-hemolytic streptococcal endophthalmitis has been linked to frosted branch response before, but it has never been associated with FBA through an immunogenic pathway. Therefore, it is important to note that idiopathic FBA can be associated with infective endocarditis and alpha-hemolytic streptococcal infections. Furthermore, FBA in elderly patients needs thorough evaluation to rule out systemic causes.