Nasal Adenocarcinoma in a Horse with Metastasis to Lung, Liver, and Bone and Review of Metastasis in Nine Horses with Sinonasal Tumors

Abstract

Sinonasal neoplasia metastasizing to distant organs is rare in horses. This case report describes the clinical and imaging findings of a horse with sinonasal neoplasia, which had metastasized to the lung, liver, and humerus. Additionally, the prevalence of sinonasal neoplasia and their incidence of distant metastasis among horses that presented to the Oregon State University Veterinary Teaching Hospital (OSU-VTH) were estimated. Of 5,558 equine patients who presented to the OSU-VTH in the last nine years, 1.4% were diagnosed with sinonasal disease and 10.3% of these cases had sinonasal neoplasia with only one having confirmed distant metastasis. This case was an eleven-year-old quarter horse which was evaluated due to a history of a right forelimb lameness of three weeks duration. Two and a half months later he presented again, this time for unilateral epistaxis and persistent right forelimb lameness. Radiography of the right elbow noted an increasingly irregular, periosteal response and osteolytic lesion of the right distal humeral condyle. At the time of the second presentation, nasosinal endoscopy identified a lobulated mass in the region of the ethmoid turbinates. Histopathology of this mass revealed an adenocarcinoma of nasal origin with metastasis to the lung, liver, and right humerus.

Clinical and Complementary Diagnosis of Sinus Neoplasia in Horses

“…Direct visualization of the neoplasm was possible in 13 out of 20 cases reported by Dixon et al [3]; the exam is also useful when there are deformities in the upper airways [23]. Cases of adenocarcinoma often present as lobulated masses in the ethmoid region, in a typical location of ethmoid hematoma [8,11], as was initially suspected in case 2. Reports of ossifying fibroma, as observed in the present case, present with historical frequency of noise and difficulty breathing [15,20].…”

“…All cases presented with purulent nasal discharge, being bilateral in 3, with a longer evolution time. There are few reports of epistaxis [8], which was initially observed in case 2, where it is suggested to be due to the involvement of the ethmoid. Increases in facial volume are common, usually firm, with no pain on palpation and greater when compared to sinusitis of dental origin [5].…”

“…Neoplasms of paranasal sinus are conditions that are difficult to characterize regarding incidence, since it is not possible to affirm how many of these cases are actually recorded [10]. Surveys of cases of sinusitis treated in reference hospitals report 2% to 19% of them are related to neoplasm [5,8,9,14,25]. Despite their low incidence, they are challenging affections due to difficult early identification because of their generally insidious onset and prolonged evolution [23].…”

Sinonasal Osteosarcoma in a Horse

“…In addition, the lesion caused by the tumor mass in expansion caused chronic sinusitis, with purulent and fetid nasal discharge at the affected site. In a retrospective study in which 5,558 horses were evaluated, sinonasal diseases were identified in 1.4% of the cases, and from these, 0.14% were nasal cavity tumors, all of them showing nasal discharge [8].…”

The Role of Computed Tomography in Imaging Non-neurologic Disorders of the Head in Equine Patients

“…Overall, the prevalence of neoplasia in horses is rather rare, but the head is a more commonly affected location in the horse ( 56 ). Differentiating various soft tissue tumor types using CT is often challenging as they share similar imaging features; however, CT provides useful information in staging the lesion by evaluating the origin, extent and vascularity of these masses ( 91 ), facilitating planning for biopsy or surgical resection. CT examination of soft tissue masses of the head should include intravenous iodinated contrast medium administration unless there is a known contraindication such as allergy.…”