Outcome of iridociliary epithelial tumour biopsies in dogs: a retrospective study

To evaluate the outcome of eyes with a confirmed iridociliary epithelial tumour (ICET) following biopsy. Forty-two specimens were selected from the Comparative Ocular Pathology Laboratory of Wisconsin database, including 11 globes enucleated following ICET biopsy and 31 iridociliary biopsies with a confirmed ICET. Histopathology was performed for all specimens. When identified, the corneal surgical wound was examined in enucleated globes. Tumour type and margins were determined for biopsy specimens and follow-up was obtained when possible. Biopsies were performed for diagnosis, debulking or excision. 30/31 biopsies had dirty margins, and iridociliary adenomas were indistinguishable from adenocarcinomas by biopsy. Upon biopsy submission 5/23 biopsies were reported as incisional and 18/23 as excisional. Follow-up information was obtained for 14/18 of those reported as excisional. 8/14 had documented recurrence within 5.0±5.6 months and 6/14 had no recurrence at 21.5±13.6 months postoperatively. Three enucleated globes were diagnosed with iridociliary adenocarcinomas and eight with iridociliary adenomas. The corneal surgical wound was sampled in 8/11 globes. There was a synechia to the surgical wound in 3/8 globes, and in 3/8 globes there were neoplastic cells within or adjacent to the surgical wound. The postoperative success of ICET excision is highly variable; complete excision is rarely achieved and recurrence is common. Biopsy effects on ocular tissues may result in synechia and other surgical complications. ICET can be diagnosed by biopsy, but adenomas are indistinguishable from adenocarcinomas.