Feline intraocular sarcoma: case report

Isabela Pessôa Barbieri Bastos1* , Camila Valério Baruel1 , Thais Fontes Braga2 ; Rayssa Dias Faleiro1 , Renan Schiebel Medeiros1 & Leonardo Rodrigues de Lima3 1Veterinarian. autonomous, Rio de Janeiro, RJ, Brasil. 2Veterinarian, Resident. Programa de Residência em Oftalmologia em Animais de Companhia, Departamento de Medicina e Cirurgia Veterinária – DMCV, Instituto de Veterinária – IV, Universidade Federal do Rio de Janeiro – UFRRJ, Seropédica, RJ, Brasil 3Veterinarian, DSc. DMCV, IV, UFRRJ, Seropédica, RJ, Brasil, RJ, Brasil


Introduction
Intraocular neoplasms are important diseases in veterinary ophthalmology. Its occurrence can impair not only the animal's vision, but also its life expectancy. Post-traumatic feline eye sarcoma, also known as feline intraocular sarcoma, is a malignant neoplasm that is often associated with trauma or chronic eye inflammation (Perlmann et al., 2011). This neoplasm is extremely aggressive, with high infiltrative capacity in intraocular structures, distant metastasis and high rates of recurrence (Dubielzig et al., 1990;Stoltz et al., 1994;Zeiss et al., 2003) The origin of post-traumatic sarcoma is still uncertain, but it has been suggested that epithelial cells of the lens, after an episode of capsular rupture, proliferate uncontrollably and develop the mesenchymal phenotype (Dubielzig et al., 1990;Wilcock, 2007;Grahn et al., 2018;).
Feline intraocular sarcoma can develop months or years after the traumatic event, involving clinical signs such as buftalmia, chronic uveitis and red eye, in addition to developing in eyes with a history of phthisis bulbi (Dubielzig et al., 2010;Perlmann et al., 2011;Slatter, 2013). The diagnosis is made based on histopathological examination after enucleation and its prognosis is nearly always unfavorable (Allgoewer, 2009). Here we report a case of post-traumatic ocular sarcoma in a cat.

Case report
A six months mixed-breed female cat with a history of being hit by a car four months before being presented. According to the owner, the accident involved eye trauma that progressed to an intense increase in the left eyeball and loss of corneal transparency. An external veterinarian prescribed systemic antibiotics, analgesics and eye drops, but the owner did not know the name of the products. The eye gradually decreased in size and the animal was referred to the ophthalmology service.
Ophthalmic examination with the aid of a magnifying glass and Finoff transilluminator showed reduced size of the left eye and intense hypotonia, which was not measurable in an applanation tonometer (TonoPen vet®). Threat response and pupillary reflex to negative light revealed an opaque cornea, but it was not possible to evaluate the anterior chamber, lens and iris. The fundoscopic examination was also impossible due to the condition. Phthisis bulbi of the left eye was diagnosed, with no signs of discomfort or irritation. The ophthalmic examination was also performed on the other eye, which did not present any changes. Enucleation of the left eyeball was indicated.
Between the preoperative evaluation period and the moment of surgery, an increase in the volume of the left eyeball and intense corneal deformity were noted (Figure 1). The eyeball was surgically removed by the enucleation procedure (

Discussion
Traumatic injuries in cats are commonly associated with falls, fights or traffic accidents, as the case reported here (Herrera, 2008).
The ocular trauma caused by being hit by a car reinforces the etiology of the formation of post-trauma neoplasm, or even chronic inflammation, due to the time that elapsed until the moment of enucleation, including phthisis bulbi. This corroborates the hypothesis that the formation of neoplasm manifests itself after chronic inflammation (Perlmann et al., 2011).
The increase in volume and corneal deformity observed in the days leading to enucleation surgery signaled that important intraocular changes were happening. This fact reinforced the hypothesis of the development of feline intraocular sarcoma (Dubielzig et al., 2010), confirmed later by histopathology.
Daleck & De Nardi (2016) discuss cases involving, besides inflammation, changes in the genome of cats that present sarcoma by application. This could also be a hypothesis in cases of feline intraocular sarcoma, taking into account what the authors say about inflammation related to the sarcoma by application, where the inflammation triggers massive release of cytokines that can influence carcinogenesis.
Another hypothesis is that post-traumatic intraocular sarcoma may be related to lens capsular rupture, with transformation of the lens epithelial cells in these cases, as mentioned by Grahn et al. (2018). In the case described here, the evaluation of some intraocular structures was impaired due to severe tissue destruction, the lens being one of these structures. Therefore, it was not possible to establish a connection between this case and the suggested hypothesis. Zeiss et al. (2003) cited the malignant transformation of the lenticular epithelium as a differential for classification of intraocular sarcoma. The reason is that although most cases of intraocular sarcomas are pure mesenchymal neoplasms, there are still different morphological diagnoses, among them leiomyosarcoma of the muscles of the iris and ciliary body, and more rarely anaplastic carcinoma of the epithelium of the ciliary body. In the case described here, an immunohistochemistry test would have enabled a more accurate diagnosis, but the animal's owner did not authorize it.
Most animals do not show signs of pain or irritation in these conditions, so many cases of phthisical eyes are not monitored or subjected to early enucleation, as occurred in here. However, according to Perlmann et al. (2011), animals have presented phthisis bulbi for years before the diagnosis of advanced intraocular sarcoma.
According to Dubielzig (2011), the trend for the occurrence of intraocular neoplasms in general, including post-traumatic sarcoma, occurs in cats from 10.6 years of age. However, in this case the cat was only six months old, indicating that even kittens and juveniles can develop sarcoma. Conceição et al. (2010) stated that primary ocular neoplasms have low metastatic potential at a distance, but Dubielzig et al. (1990), Stoltz et al. (1994) and Zeiss et al. (2003) all described intraocular sarcoma as potentially metastatic.
In general, sarcomas have a high rate of local recurrence, so aggressive surgery is indicated. The recommended surgical margin is at least 3 cm, but the ideal margin is least 5 cm (Daleck & De Nardi, 2016). In cases of intraocular sarcoma or other ocular neoplasms, there is no wide margin for removal. The reason is that most surgically accessible eye structures are limited to the interior of the orbit, and even the orbit itself. Therefore, early diagnosis is necessary. Dubielzig et al. (1990) cited complications such as blindness and neurological signs caused by neoplastic infiltration through the optic nerve, optic chiasm and brain, diagnosed after euthanasia.

Conclusion
In the case described, enucleation occurred only four months after the traumatic event, but even so the diagnosis was of sarcoma at an early stage. Therefore, the clinical suspicion of intraocular sarcoma should be considered in cats with phthisis bulbi, especially after a traumatic event. In these cases, enucleation should be considered as a therapeutic approach to prevent the development of sarcoma, which is extremely aggressive and has high metastatic potential.