Case report: Medical and surgical management of presumed canine nodular granulomatous episcleritis with progression to posterior nodular scleritis, choroiditis, and optic neuritis

Nodular granulomatous episcleritis (NGE) typically presents as an elevated mass or elevated masses at the limbus and often infiltrates the cornea (episclerokeratitis). In the current report, a granulomatous lesion was observed subretinally in the right eye (OD) of a 5-year-old male castrated American Staffordshire Terrier dog. There was concurrent retinal hemorrhage and detachment OD; the right eye was not visual. Due to poor prognosis for vision and potential for a neoplastic etiology of the mass, staging with higher imaging was recommended but declined by the owner. Therefore, an enucleation was performed. Histopathology of the globe identified a subretinal mass, marked histiocytic and lesser lymphoplasmacytic choroiditis, posterior episcleritis, and optic neuritis with retinal detachment. The subretinal mass was composed of densely packed, large, spindle histiocytes mixed with occasional lymphocytes, plasma cells, and only rare neutrophils. Regions of the mass showed lymphocytes aggregate to form nodules. This histological presentation was a type of proliferative histiocytic disease with similarities to nodular granulomatous episcleritis or granulomatous/necrotizing scleritis. This is a novel presentation of NGE-like progression to subretinal scleral, choroidal, and retinal involvement and provides a new differential possibility for posterior segment masses observed on fundic examination.