Computed Tomographic and Histopathological Characteristics of 13 Equine and 10 Feline Oral and Sinonasal Squamous Cell Carcinomas

Abstract

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.

Conventional imaging is useful for assessment of equine pharyngeal squamous cell carcinoma but underestimates bone involvement

“…Few studies report SCC in uncommon locations of the head and throat regions in equine patients. A recent case series reporting the CT appearance of 13 equine oral and sino‐nasal SCC identified the paranasal sinuses as the mass centre in the majority of cases; in this study, alternative locations were the mandible and the tongue, but none of the identified masses were centred on the pharyngeal region (Strohmayer et al, 2020).…”

Invasive squamous cell carcinoma causes trigeminal nerve dysfunction in a horse

“…Due to its infiltrative nature, it is plausible that the current neoplasm represents the local extension from a primary neoplasm originating from either the oral or respiratory mucosa, whose primary site has not been appreciated during post‐mortem examination. This tumour exhibited high grade malignancy, with the histologic malignancy score of 23 out of 24 following the grading system described by Strohmayer et al (2020), which is equivalent to grade IV on the human malignancy grading system described by Anneroth et al (1987). This is consistent with the findings of a review of equine SCCs, where most horses (13/14) had categorisation as grade 3 or above with a highly invasive nature (Strohmayer et al, 2020).…”

“…This tumour exhibited high grade malignancy, with the histologic malignancy score of 23 out of 24 following the grading system described by Strohmayer et al (2020), which is equivalent to grade IV on the human malignancy grading system described by Anneroth et al (1987). This is consistent with the findings of a review of equine SCCs, where most horses (13/14) had categorisation as grade 3 or above with a highly invasive nature (Strohmayer et al, 2020).…”

Advances in the Diagnosis of Equine Respiratory Diseases: A Review of Novel Imaging and Functional Techniques

“…Precise diagnosis via CT has been emphasized in order to avoid unviable treatment approaches [27]. Malignant and benign tumors of the nasal and paranasal sinuses including squamous cell carcinoma, undifferentiated carcinoma, hemangiosarcoma, nasal adenocarcinoma, myxoma, chondroblastic osteosarcoma, anaplastic sarcoma, and fibro-osseous lesions have been described [28][29][30][31]. Henninger et al provided detailed CT descriptions regarding the most common features of sinusitis and alveolitis [32].…”