Intraocular Osseous Metaplasia in Norfolk Black Turkey (Meleagris gallopavo): Clinicopathological Characterization of a Rare Avian Condition.

Abstract

BACKGROUND: Osseous metaplasia is a rare condition characterized by abnormal bone growth in soft tissues. Although documented in mammals, intraocular osseous metaplasia is uncommon in avian species and has been poorly characterized in turkeys (Meleagris gallopavo). CASE PRESENTATION: An adult Norfolk Black turkey presented with progressive buphthalmos, caseous ocular discharge, and complete vision loss confined to the left eye. Owing to the poor prognosis, enucleation was performed. Gross examination revealed a friable, caseous, yellow-white intraocular mass with retinal and vitreous involvement. Histopathological examination revealed abundant osteoid matrix and osseous trabeculae, intense neovascularization, heterophilic infiltration, and areas resembling the medullary bone. DISCUSSION: Histopathological findings support the diagnosis of intraocular osseous metaplasia, which is distinct from normal scleral ossicles in birds. Chronic inflammation and longstanding retinal detachment may trigger differentiation of retinal pigment epithelium (RPE) into osteoblast-like cells, contributing to osseous metaplasia in the ciliary body. Intraocular bone formation in birds remains poorly understood, and further investigation of its pathogenesis is warranted. CONCLUSION: This report describes a well-characterized case of intraocular osseous metaplasia in a turkey. Recognition of this uncommon condition is essential when considering the differential diagnoses of intraocular masses in avian species, emphasizing the diagnostic value of histopathological evaluation. Further studies are warranted to explore the possible systemic involvement and to elucidate the underlying etiologies, including chronic inflammation and trauma.