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

Abstract

Summary Background Squamous cell carcinoma is the most common pharyngeal neoplasm but is poorly documented with diagnostic imaging in veterinary literature. Objectives To describe the diagnostic imaging findings in horses with confirmed pharyngeal squamous cell carcinoma. Study design Retrospective case series. Methods Horses with a definitive diagnosis of pharyngeal squamous cell carcinoma based on in situ biopsy and/or cytology were identified in 2 different centres. Multi‐modality imaging findings are reported. Results Six equids were included. On radiographic examination, increased pharyngeal opacity and reduction of pharyngeal lumen were observed in all horses, centred on the oropharynx (three cases), the laryngopharynx (two cases) or the nasopharynx (one case). A clearly delineated mass was visualised in four cases. Additional radiographic findings were border effacement of the epiglottis (5/6) or soft palate (3/6), thickening of the pharyngeal walls (4/6) or soft palate (3/6) and suspected retropharyngeal lymphadenomegaly (3/6). Ultrasonography was useful to highlight retropharyngeal (4/6) and mandibular (4/6) lymphadenopathy suggestive of metastatic dissemination. Computed tomographic images were available for two horses and detected bone lysis not visible on radiographs. Main limitations The number of cases was low, and computed tomography was not realised in all cases. Conclusions Findings support the usefulness of radiography and ultrasonography in horses with suspected pharyngeal neoplasia for a first‐line imaging diagnosis, in particular when endoscopy is impaired by a mass effect or dyspnoea. Computed tomography gives a more accurate assessment of bone involvement.

Ultrasonographic technique and appearance of presumptively normal clinically relevant lymph nodes in horses

“…Ultrasonography is largely used in human medicine and small animal veterinary medicine to identify and evaluate lymph nodes (Mayer et al, 2010; Pugh, 1994; Schreurs et al, 2008) and abnormal lymph nodes are easily recognised at ultrasonography (Agthe et al, 2009; de Swarte et al, 2011; Kinns & Mai, 2007; Nyman et al, 2005; Pattanayak et al, 2018; Taeymans et al, 2011). In horses, ultrasonographic features of abnormal lymph nodes have been sporadically reported (de Clercq et al, 2003; Evrard et al, 2015; Janvier et al, 2016; Vandersmissen et al, 2022; Vaughan et al, 2013). The present description of anatomical landmarks and ultrasonographic features in healthy horses will help the practitioners in finding specific lymph node groups and recognising abnormal lymph nodes.…”

“…Anatomy of the equine lymph nodes is well described in textbooks (Barone, 1996;Budras et al, 2008;Kidd et al, 2014;Orsini & Sack, 2003;Sisson & Grossman, 1953). Lymphadenopathy with enlargement and hypoechogenicity of lymph nodes is reported in inflammatory, infectious and neoplastic disorders in horses (Evrard et al, 2013(Evrard et al, , 2015Vandersmissen et al, 2022;Vaughan et al, 2013); however, there are only few descriptions of ultrasonographic technique and normal appearance of lymph nodes in horses, each referring to a separate lymph node group (Evrard et al, 2013(Evrard et al, , 2015Janvier et al, 2016;Rathmanner & Rijkenhuizen, 2012;Scott & Hughes, 2017;Vaughan et al, 2011Vaughan et al, , 2013.…”

“…and abnormal lymph nodes are easily recognised at ultrasonography(Agthe et al, 2009;de Swarte et al, 2011;Kinns & Mai, 2007;Nyman et al, 2005;Pattanayak et al, 2018;Taeymans et al, 2011). In horses, ultrasonographic features of abnormal lymph nodes have been sporadically reported (de Clercq et al, 2003; Evrard et al, 2015; Janvier F I G U R E 1 Positioning of the microconvex transducer to assess the medial retropharyngeal lymph nodes at the angle of the mandible et al, 2016;Vandersmissen et al, 2022;Vaughan et al, 2013)…”