Squamous cell carcinoma (SCC) is the most common equine sinonasal and feline oral tumour. This study aimed to describe the computed tomographic and histopathological characteristics of equine and feline SCC. Thirteen horses and 10 cats that had been histopathologically diagnosed with oral or sinonasal SCC and had undergone computed tomography (CT) of the head were retrospectively included in the study. CT characteristics of the mass and involved structures were noted. Histological examinations were evaluated according to a human malignancy grading system for oral SCC, which considered four grades of increasing aggressiveness. In horses, the masses were at the levels of the paranasal sinuses (n = 8), mandible (n = 3), tongue (n = 1), and nasal cavity (n = 1). In cats, the masses were at the levels of the maxilla (n = 4), mandible (n = 3), tongue (n = 1), and buccal region (n = 1) and were diffusely distributed (facial and cranial bones; n = 1). Masses in the equine paranasal sinuses showed only mild, solid/laminar, periosteal reactions with variable cortical destruction. However, maxillary lesions in cats showed severe cortical destruction and irregular, amorphous/pumice stone-like, periosteal reactions. CT revealed different SCC phenotypes that were unrelated to the histological grade. For morphologic parameters of the tumour cell population, a variability for the degree of keratinization and number of mitotic cells was noted in horses and cats. Concerning the tumour-host relationship a marked, extensive and deep invasion into the bone in the majority of horses and cats was seen. Most cases in both the horses and cats were categorized as histological grade III (n = 8); four horses and one cat were categorized as grade IV, and one horse and one cat were categorized as grade II. In this study, we examined the diagnostic images and corresponding applied human histopathological grading of SCC to further elucidate the correlations between pathology and oral and sinonasal SCC imaging in horses and cats.

鳞状细胞癌（SCC）是最常见的马鼻窦和猫口腔肿瘤。这项研究旨在描述马和猫SCC的计算机断层扫描和组织病理学特征。回顾性研究包括13匹马和10只猫，它们经组织病理学诊断为口腔或鼻窦SCC，并经过了头部计算机断层扫描（CT）。记录肿块和相关结构的CT特征。根据人类恶性肿瘤口服SCC评分系统对组织学检查进行了评估，该系统考虑了四个级别的侵略性增强。在马中，肿块处于鼻旁窦的水平（ñ = 8），下颚（ñ = 3），舌头（ñ = 1）和鼻腔（ñ= 1）。在猫中，肿块处于上颌骨的水平（ñ = 4），下颚（ñ = 3），舌头（ñ = 1）和颊区域（ñ = 1），且分布广泛（面部和颅骨； ñ= 1）。马鼻旁窦的肿块仅显示轻度，实心/层状，骨膜反应，并伴有皮质破坏。然而，猫的上颌病变显示出严重的皮质破坏和不规则的无定形/浮石样骨膜反应。CT显示不同的SCC表型与组织学分级无关。对于肿瘤细胞群的形态学参数，在马和猫中注意到了角化程度和有丝分裂细胞数量的变化。关于肿瘤与宿主的关系，在大多数的马和猫中，可见到明显，广泛而深入的侵入骨中。马和猫的大多数病例都被分类为组织学等级III（ñ= 8）; 四匹马和一只猫被归为IV级，一匹马和一只猫被归为II级。在这项研究中，我们检查了SCC的诊断图像和相应的人类组织病理学分级，以进一步阐明马和猫的病理学与口腔和鼻窦SCC成像之间的相关性。