Presumed primary intraocular chondrosarcoma in cats

Abstract

Following unilateral enucleation, 4 Domestic Shorthair cats with an average age of 12.5 years (range: 9–16 years) were histologically diagnosed with a presumed primary intraocular chondrosarcoma at the Comparative Ocular Pathology Laboratory of Wisconsin (Madison, Wisconsin). Medical records and follow-up were available for 3 of the 4 cats. Clinically, only 1 eye was affected in each cat; a mass lesion was noted in 2 cats, and a neoplasm was suspected in the other 2 cats. Grossly, 3 tumors presented as coalescing, poorly demarcated, white, friable masses filling the vitreous and intraocular chambers; 1 tumor presented as a solitary, well-demarcated, tan mass involving the iris and ciliary body. Histologically, all 4 neoplasms were composed of haphazardly arranged plump neoplastic spindle cells surrounded by irregular islands and thick trabeculae of abundant, variably basophilic, and Alcian blue–positive chondromatous matrix. None of the cats presented histologically or clinically with signs suggestive of feline posttraumatic ocular sarcoma. Two cats are still alive and healthy 6 months and 3 years following enucleation. One cat died 6 months following enucleation; however, this cat suffered from poorly controlled diabetes mellitus, and the cause of death is undetermined. No other tumors or skeletal lesions were identified that could suggest a metastatic tumor to the eye. The origin of primary intraocular chondrosarcoma is unclear, but is presumed to be ocular multipotent mesenchymal stem cells. Four cases of intraocular chondrosarcoma in cats not associated with the posttraumatic sarcoma complex of intraocular tumors are described.