Parotid salivary gland carcinoma in a geriatric horse

Abstract

SummaryThis case report describes a geriatric gelding with a 2 month history of fast-growing masses within the parotid and submandibular regions. The horse was dyspnoeic on presentation and upper airway endoscopy revealed partial airway obstruction at the level of the pharynx, secondary to a space-occupying mass. Cytological evaluation of multiple fine-needle aspirates obtained from the masses were suggestive of salivary gland neoplasia, therefore the horse was subjected to humane euthanasia. A computed tomographical scan was obtained post mortem and revealed a large multi-lobulated mass involving both guttural pouches, resulting in 80% occlusion of the naso-and oropharynx. Histopathology confirmed a parotid salivary gland carcinoma (papillary-cystic type). Salivary gland tumours are extremely rare in horses, with only a few cases reported in the literature. Treatment of these malignancies proves to be challenging, requiring complete parotidectomy or surgical debulkment, in combination with adjunctive therapy.

Partial parotid sialoadenectomy in a horse with parotid ductal carcinoma: Surgical description and case report

“…Five types of salivary gland tumors have been identified in horses and include adenoma, mucoepidermoid tumor, acinic cell tumor, carcinoma, and unclassified tumors 3,7 . In our gelding, the histologic presence of striated and intercalated ducts abutting the tumor and pattern of comedonecrosis with absence of secretory vesicles were consistent with parotid ductal carcinoma.…”

“…Total or partial parotid sialoadenectomy is the most commonly reported successful treatment in humans, dogs, and cats with parotid gland carcinoma 12,13 . In horses, parotidectomy has been advised against due to the complicated regional anatomy 1,7 . We believe that advances in surgical equipment, including access to a vessel sealing devices, enabled the parotid sialoadenectomy to be performed more easily and safely.…”

“…Like humans, carcinoma is the most common parotid neoplasia in dogs 3 . Primary parotid neoplasia is rare in horses; melanoma is the most common tumor type, followed by carcinoma 3,6–8 . Treatment by total or partial parotidectomy combined with more radical resection in advanced disease can result in long‐term survival in humans 4 .…”

Application and indications of magnetic resonance imaging and computed tomography of the equine head

“…The use of CT and MRI is usually restricted to masses that need further evaluation for diagnostic or treatment planning purposes. Compared with ultrasound, CT and MRI provide better coverage of the entire lesion on the images (larger field of view), allow using multiple imaging planes (or even 3D models) and allow visualisation of tissues covered by gas or bone (Fig 14b,d) (Ramirez and Tucker 2004;Wollanke et al 2006;Gerlach et al 2007;van den Top et al 2007;Jakesova et al 2008;Pekarkova et al 2009;Naylor et al 2010a;Schneider et al 2010;Santos et al 2012;Bienert-Zeit et al 2014;McConnell et al 2014). The use of contrast media aids in determining the exact lesion demarcation and assessment of potential invasion into the surrounding tissues.…”

“…2014; McConnell et al . 2014). The use of contrast media aids in determining the exact lesion demarcation and assessment of potential invasion into the surrounding tissues.…”