Histomorphologic and immunohistochemical characteristics of intraocular metastatic carcinomas of presumed pulmonary origin in cats: A retrospective case series from 2019 to 2025

Carcinomas have been reported to metastasize to the globe, specifically the uvea; however, the distinguishing histologic features of intraocular metastatic carcinomas in cats are not well-documented. Eleven cases of feline ocular biopsies with intraocular metastatic carcinomas and history of a pulmonary mass submitted to the Comparative Ocular Pathology Laboratory of Wisconsin from 2019 to 2025 were collected and reviewed. Alcian blue stains and immunohistochemical markers for thyroid transcription factor-1 and vimentin were evaluated. No significant sex or breed predispositions were identified. Uveitis, glaucoma, and the presence of an ocular mass were the most common clinical reasons for enucleation. All cases had a thoracic mass identified by radiographs prior to enucleation. All neoplasms had carpeting to gland-forming growth patterns lining surfaces of intraocular structures, affecting the anterior uvea. Goblet cells were highlighted with Alcian blue staining in 7/11 cases (64%). Neoplastic cells immunolabeled for thyroid transcription factor-1 in 2/11 cases (18%) (neither of which had goblet cells) and vimentin in 4/11 cases (36%). Based on this study, feline intraocular metastatic neoplasms are commonly associated with glaucoma and less commonly with uveitis. Histomorphologic and immunohistochemical features of pulmonary origin neoplasia were not consistently found in these metastatic masses of suspected pulmonary origin; the presence of goblet cells was the most commonly identified histologic feature.