Abstract
Purpose:
To describe a case series of pleomorphic iridociliary adenocarcinomas in dogs.
Methods:
The COPLOW database was mined for cases of canine pleomorphic iridociliary adenocarcinomas. Cases were reviewed and described, and additional clinical data were collected and summarized. Immunohistochemical staining was performed on a subset of cases.
Results:
There are 22 cases of canine pleomorphic iridociliary adenocarcinomas in the COPLOW collection representing 1.5% of all canine iridociliary epithelial tumors. The average age at enucleation was 10.9 years and there were 13 males and 8 females. There were 7 Labrador retrievers, 4 golden retrievers, 2 shih tzus, 3 mixed breeds and a single dog from the following breeds: border collie, Shetland sheepdog, boxer, vizsla, Maltese, dachshund. Elevated intraocular pressure, uveitis, corneal disease and hyphema were common presenting complaints. Seven cases (31.8%) had a history of chemical ciliary body ablation with an intravitreal gentamycin injection and three (13.6%) had known or suspected ocular trauma. All had a history of ocular abnormalities for months to years. Histologically, the tumors are composed of cuboidal to polygonal cells forming cords, trabeculae and sheets with variably prominent PAS-positive basement membranes and exhibit extensive invasion of intraocular structures and/or sclera. Of the tumors stained immunohistochemically, the neoplastic cells stain positively for vimentin and variably positive for pancytokeratin.
Conclusions:
These canine neoplasms represent the most malignant of tumors arising from the anterior uvea and share histologic and immunohistochemical features with human pleomorphic adenocarcinomas of the ciliary body. The development of these tumors in canine globes is associated with a history of chemical ciliary body ablation, trauma and long standing ocular disease.