Nodular histiocytic iritis causing iris lumps in young UK dogs

Abstract

PURPOSE: The aim of this study was to describe the clinical presentation, histopathology, management, and outcome of nodular histiocytic iritis, an intraocular variant of nodular granulomatous episcleritis (NGE). METHODS: A retrospective review of the medical records of five dogs with intraocular NGE-type inflammation as diagnosed by histopathology. RESULTS: Four Border Collies and one crossbreed dog, aged 1.5-3.4 years (mean age 2.38 years). The clinical presentation was an extensive, raised, pale iris lesion of variable location. All cases were unilateral. The physical examination was normal. Complete blood count/serum biochemistry (n = 1) and thoracic radiography (n = 1) were normal. Ocular ultrasound (n = 2) was normal apart from increased iris thickness. Enucleation (n = 4) or excisional biopsy (iridectomy, n = 1) was performed because of suspected neoplasia. Following enucleation, the remaining, contralateral eye did not develop additional lesions (9 days-3.7 years follow-up). There was no recurrence following sector iridectomy with 5 months topical 1% prednisolone acetate (3.9 years follow-up). The histopathologic findings in all five cases indicated a focal histiocytic and lymphoplasmacytic anterior uveitis (iritis), similar to that seen in cases of NGE. CONCLUSION: Nodular histiocytic iritis presents as unilateral iris thickening in isolation and young Collies appear to be predisposed. The histopathological findings are similar to NGE. Although the clinical presentation resembles intraocular neoplasia, an inflammatory process should be considered, which may be amenable to medical management. Definitive diagnosis may be obtained by iris sampling.