Squamous Cell Carcinoma in a Pig

Abstract

Background: Squamous cell carcinoma (SCC) is a malignant neoplasm of epidermal cells that exhibits keratinocyte differentiation. These neoplasms are common in dogs, cats, horses, and cattle, relatively uncommon in sheep, and rarely affect goats and pigs. There are several factors that are associated with the development of SCC, including prolonged exposure to ultraviolet light, lack of pigment in the epidermis, and sparse coating or lack of fur at the affected sites. The aim of this study was to report the occurrence of squamous cell carcinoma in a domestic pig.Case: A surgically removed nodule from the left ear of a female, light-colored, three-year-old pig, which breed was not defined, was submitted for histopathological analysis. The sample was fixed in 10% formalin, analyzed macroscopically, routinely processed for histology, sectioned at five microns and stained with hematoxylin and eosin. Additionally, anticytokeratin (AE1/AE3) and anti-vimentin immunohistochemical assays were performed. All additional information was provided by the animal’s owner. According to the history obtained, the animal belonged to a herd made up of five females and one boar. For four months, multiple nodules started to grow on the outer surface of the pig’s ear and in many occasions exhibited ulceration and bleeding. One of the nodules was submitted for histopathology examination. Macroscopically it measured 3 cm in diameter, had an irregular and ulcerated surface, and a wide base. Cut surface had a firm consistency and whitish color. Microscopic examination revealed proliferation of neoplastic epithelial cells arranged in islands and trabeculae, with slightly eosinophilic cytoplasm, pleomorphic, round, reniform nucleus, with loose chromatin and 1-3 nucleolus. Mitotic figures were infrequent. In the central area of the islands, there was individual cell keratinization. There was a moderate, fibrovascular supporting stroma with intense inflammatory infiltrate composed of lymphocytes, plasma cells and eosinophils. Anti-cytokeratin (AE1/AE3) immunohistochemical assay (IHC) revealed a strong diffuse positive staining on the cytoplasm of tumoral epithelial cells, and anti-vimentin IHC showed positive staining on the supporting tissue cells (fibroblasts and endothelial cells).Discussion: The diagnosis of squamous cell carcinoma in this pig was based on clinical and pathological findings since it was observed proliferation of neoplastic epithelial cells often forming “keratin pearls” and immunohistochemistry positive for cytokeratin was immunostaining in the cytoplasm of tumor cells. Information on the occurrence of SCC in pigs is scarce in the literature, especially in Brazil. In a survey of neoplasms in farm animals in Southern Rio Grande do Sul with cases from 1978 to 2002, neoplasms in pigs represented 0.6% of the diagnoses when compared to the number of neoplasms in cattle and horses. The low number of cases in this species is due to the fact that a large proportion of the population is slaughtered at a young age and therefore the chances to develop neoplasms are lower. The main SCC growth sites include areas deprived of hair, especially in animals with unpigmented skin. In the pig described here, the neoplasm was located on the outer surface of the ear, which was exposed to ultraviolet rays. Granuloma, papilloma, and basal cell tumor should be considered in the list of differential diagnosis when SCC is suspected. Neoplasms in pigs are scarcely reported.Keywords: neoplasm, carcinoma, pig, immunohistochemical.

Vulvo-vaginal epithelial tumors in mares: A preliminary investigation on epithelial-mesenchymal transition and tumor-immune microenvironment

“…40,46,55 Growing evidence has suggested that equus caballus papillomavirus type 2 (EcPV2) is likely the etiological cause of equine SCCs, including penile and preputial SCC, 40,46 as well as equine vulvo-vaginal carcinoma. 35,38,46,55 In the last decade, numerous studies have investigated the prevalence and the possible role of EcPV2 in inducing penile and preputial epithelial preneoplastic lesions and both benign and malignant tumors. 46 However, the role of EcPV2 in the pathogenesis of genital lesions in mares remains elusive.…”

“…46 However, the role of EcPV2 in the pathogenesis of genital lesions in mares remains elusive. 17,35,38,43,55 Similar to the equine male counterpart, vulvo-vaginal carcinoma represents a malignant tumor that can occur with a de novo onset or arise from precursor lesions, such as plaques and papillomas. 52,53 Recently, different equine SCCs have been reported to undergo the epithelial-to-mesenchymal transition (EMT) process.…”

Mucocutaneous Squamous Cell Carcinoma in a Yucatan Minipig

“…2 -4 Oral and cutaneous squamous cell carcinomas have been infrequently reported in pot-bellied pigs kept as pets and may occur in farm pigs as well. 6- 11…”

“…[2][3][4] Oral and cutaneous squamous cell carcinomas have been infrequently reported in pot-bellied pigs kept as pets and may occur in farm pigs as well. [6][7][8][9][10][11] In animals and humans, including swine, there is an association between squamous cell carcinoma and ultraviolet (UV) light exposure. 9,[12][13][14] This was considered unlikely in this case, as this animal was housed indoors at both the breeding facility and the research facility and thus not exposed to UV light.…”

“…[6][7][8][9][10][11] In animals and humans, including swine, there is an association between squamous cell carcinoma and ultraviolet (UV) light exposure. 9,[12][13][14] This was considered unlikely in this case, as this animal was housed indoors at both the breeding facility and the research facility and thus not exposed to UV light. Additionally, solar elastosis and actinic keratosis, which are commonly observed in UV-associated neoplasms, were not observed in this case.…”