Computed Tomographic Appearance of Equine Sinonasal Neoplasia

Abstract

The computed tomography (CT) features of tumors involving the nasal cavity and/or paranasal sinuses of 15 horses were reviewed. The 15 tumors included five neuroendocrine tumors/neuroblastomas, two undifferentiated carcinomas, two myxosarcomas, and one each of nasal adenocarcinoma, hemangiosarcoma, chondroblastic osteosarcoma, anaplastic sarcoma, myxoma, and ossifying fibroma. All tumors except the ossifying fibroma were iso- or hypoattenuating relative to masseter muscle. Thirteen of the fifteen tumors exhibited moderate or marked osteolysis of adjacent cortical bone and 14/15 were characterized by destructive changes of the nasal turbinates, nasal septum, and/or infraorbital canal. Ten horses had moderate or marked involvement of the cribriform plate and six had clear intracranial extension of the mass. CT features were compared to radiographic findings for 10 horses. A mass was observed in 10/10 radiographic studies and mass within the caudal maxillary sinus (7/8) and rostral maxillary sinus (6/7) was identified correctly in most horses. The radiographs were least sensitive for identifying masses within the sphenopalatine sinus (0/5), cranium (0/4), and retrobulbar space (1/7) compared to CT. The radiographs also underestimated potential features of malignancy, such as severity of osteolysis or osseous production. While radiographs are a useful screening tool for identification of sinonasal masses, CT provides greater information regarding mass extent, features of malignancy, and important prognostic indicators.

Two- and Three-Dimensional Anatomy of Paranasal Sinuses in Arabian Foals

“…Although CT has widespread use in veterinary medicine, especially in small animals, it has limited use in equine clinics, because of the lack of availability of appropriate devices and the current devices being able to scan only the head and distal legs of horses [17, 19, 37]. CT is used in horses to investigate the gross sectional anatomy [1, 7] of the head as well as pathologic conditions arising in this area, such as sinusitis [36, 37], alveolitis [13], trauma [3, 22] and carcinomas [6, 42]. These studies have investigated horses of different breeds and ages other than Arabian foals, primarily via transverse CT images and have provided many details about the paranasal sinuses [7, 23, 29, 36, 37].…”

Congenital mandibular myxosarcoma in a foal

“…Complete surgical excision is the treatment of choice, with the goal of clean surgical margins (Lin and others 2006); recurrence can be expected with incomplete excision. Because radiography may underestimate the extent of the tumour, CT should, if possible, be used to determine the tumour margins prior to surgery (Cissell and others 2012). In this case, partial hemimandibulectomy at the time of initial diagnosis might well have been curative, and such radical resection and reconstruction would likely have been accommodated well in such a young foal.…”

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

“…However, in cases of sinonasal neoplasia where surgery is warranted or further prognostic information is desired CT and MRI have shown to be beneficial [16,17]. The advantages of CT include the ability to better evaluate disease extension, assess involvement of surrounding osseous structures, and more precisely localize the disease [16]. MRI has been suggested to be more accurate than CT to determine the degree of brain involvement as well as damage to the soft tissues surrounding the orbit.…”

“…In this case radiography was the only imaging modality done, as treatment was not pursued. However, in cases of sinonasal neoplasia where surgery is warranted or further prognostic information is desired CT and MRI have shown to be beneficial [16,17]. The advantages of CT include the ability to better evaluate disease extension, assess involvement of surrounding osseous structures, and more precisely localize the disease [16].…”