Squamous Cell Carcinoma in Third Eyelid of Cat
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Background: The third eyelid neoplasms are uncommon in cats. The squamous cell carcinoma are easily found in head and neck of same specie, although is unusual in eye region. The more commun localization is eyelid and eyeball, being 60 and 15%, respectively. It could bee diagnosed by citology, histopathology, imunohistochemistry and molecular biology. The surgery is more effective treatment, because the tumor can be totally removed and it must available surgical margin. The aim of this study was to report a case of squamous cell carcinoma in third eyelid of a cat and show how it was treated with radical surgery. Case: A 11-year-old spayed female domestic short-haired white and black colored cat was presented for evaluation at Maria Dias Teixeira Hospital of Amazonia Federal Rural University (UFRA), of an red ocular mass fast growth in the left eye for 2 months. Physical exam was within normal limits. The animal presented discomfort on the region, when it was manipulated. The mass was ulcerated and blood-tinged ocular discharge, had 3.3 x 2 cm, beginning on third eyelid and overlay all the eyeball. Blood was collated to make exams. Complete blood count and serum chemistry profiles were within normal ranges, but leukocytes were increased and it was treated with Amoxicillin (22 mg/kg). It was performed biopsy to histopathology and immunohistochemistry diagnose, and radiography and ultrasonography to found metastasis. Ocular tissues were fixed in 10% formalin and processed routinely for histological examination. Sections were stained with hematoxylin and eosin and diagnosed poorly differentiated Squamous cell carcinoma. Immunohistochemistry was performed using anti-cytokeratin 1: 200, anti-vimentin 1: 150 and anti-actin alpha smooth muscle 1: 700 antibodies. The tumor cells were positive for cytokeratin and negative for vimentin. In tumor stroma was immunostaining of myofibroblasts by actina alpha smooth muscle. Because of malignment and infiltrative neoplasm, it was chosen to perform eye and eyelid enucleation. At post-operative evaluation no complication was found and in tem days, surgical wound was held. Seven months post-operative no neoplastic tissue had growth on local. Discussion: A retrospective study at Belem and some close cities, which took all neoplasms and classified, found only 1.5% of ocular neoplasms, and no one was in cats. Similarly occurred with another study, that 1.21% out of ocular masses, just 12.5% was diagnosed in cats, showing how uncommon is ocular neoplasm in cats. Including theses lesions, less of then are only in third eyelid. Ultraviolet radiation is the most related probably causes of squamous cell carcinoma. At Belem City ultraviolet radiation is very high, can bee 11 in some stations, in a scale of 0 to 14, the medial temperature is 27 degrees C. Another factor that could influence squamous cell carcionoma progress is skin color, animals' wich skin is light have more probably to develop this neoplasm. On our case, close to eye, skin was dark, although the carcinoma was growth at third eyelid mucosa, a local that have no protection to ultraviolet radiation. Myofibroblasts observed in the tumor stroma are important in the invasion process of this tumor in humans. The treatment used in this case was radical surgery, with no other adjuvant, what is indicate for some authors. Another authors prefer exscind only third eyelid, but sometimes it is not possible, because this kind of neoplasm is very infiltrate. The localization and the nodular form of squamous cell carcinoma found in this study is uncommon, mainly in cats. Histopathological and immunohistochemical analysis were important for definitive diagnostic. The treatment by enucleation of eyeball and removing the eyelids was effective, without relapse in 7 months after surgery.