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

Abstract

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.

Four cases of iridociliary tumors in domestic rabbits (Oryctolagus Cuniculus)

“…Iridociliary tumors display significant variability in pigment content and the number of mitotic figures, so degree of malignancy is assessed based on scleral invasiveness . Metastatic potential of iridociliary tumors is generally considered to be low for both adenomas and adenocarcinomas.…”

“…Metastatic potential of iridociliary tumors is generally considered to be low for both adenomas and adenocarcinomas. There are three cases of confirmed metastasis in the veterinary literature and three other cases of dogs with confirmed iridociliary tumors that later developed evidence of neoplasia in other parts of the body that were not histologically confirmed to represent metastasis . To the authors’ knowledge, there have been no other reported cases of bilateral iridociliary carcinoma, and it is unclear in Case 1 if the two lesions evolved separately or if one represented metastasis of the other.…”

“…Iridociliary adenomas and carcinomas are tumors that arise from the epithelium of the iris and ciliary body. They are the second most commonly reported intraocular tumor in dogs and are occasionally reported in cats and humans . Morphology varies widely by species and between individuals; tumors may be pigmented or nonpigmented and can be papillary, solid, or cystic .…”

“…However, histopathology is often required to differentiate iridociliary tumors (which are rare in humans) from melanoma . In veterinary medicine, incisional/excisional biopsy has been reported in dogs, but is associated with a high incidence of postoperative complications and risk of recurrence …”

What is your diagnosis? Aqueous humor from a dog

“…Distant metastases of iridociliary carcinomas are extremely rare . The prognosis for survival in dogs and cats with ciliary body adenomas and adenocarcinomas is good, although the prognosis for the globe retention is poor as enucleation is required in most cases …”