MRI can show the size, extent and invasion of nasal soft tissue lesions clearly, and to some extent, allow for a judgement about the composition of the lesions ( 14). It has been confirmed that magnetic resonance imaging (MRI) can depict soft tissue with high contrast in imaging examinations of the equine nasal cavity ( 13). Computed tomography (CT) scans can reveal the presence of a space-occupying lesion involving the nasal passage in small ruminants, and help in the diagnosis of ENA sheep lesions ( 3, 11, 12). Imaging techniques are important diagnostic tools but have not always been used sufficiently in goats. Gross evaluation, cytology, histopathology, PCR, and transmission electron microscopy are helpful for the diagnosis of ENA ( 8– 10). At necropsy, the tumors may be bilateral or more commonly unilateral. Most of the nasal cavity is filled with tumor tissue before clinical symptoms appear. Usually, the clinical symptoms are slowly progressive. Electron microscopic and histochemical studies have shown that the tumors may originate either in olfactory or respiratory mucosal glands ( 7).
These tumors have been classified histologically as low grade adenocarcinoma, and their target tissues are secretory epithelial and mesenchymal cells of the ethmoid bone in the nasal cavity ( 6). ENTV-2 shares an oncogenic mechanism with enzootic nasal tumor virus type 1, and its oncogenic proprieties are associated with env gene products ( 5). Enzootic nasal tumor virus type 1 and enzootic nasal tumor virus type 2 (ENTV-2) are causative agents of ENA in sheep and goats, respectively, and both are β-retroviruses ( 4). It occurs naturally in many countries ( 1– 3). In conclusion, CT and MRI have high diagnostic values for enzootic nasal tumors because they match the postmortem findings and are more accurate than radiography.Įnzootic nasal adenocarcinoma (ENA) is a neoplasia induced by viral infection in sheep and goats. After dissection, histopathological examination of the mass and virus genome detection of the nasal secretions confirmed that the intranasal mass was a low-grade adenocarcinoma and that the goats were infected with enzootic nasal tumor virus type 2. On MRI, the mass exhibited equal or slightly higher signal intensity on T2 weighted images, equal signal intensity on T1 weighted images, a high signal on fluid-attenuated inversion recovery images and heterogeneous enhancement postcontrast. The nasal concha was destroyed and the paranasal sinus mucosa was thickened and filled with fluid in some goats. Head radiographs showed increased density of the unilateral or bilateral nasal cavity in four goats, and a CT scan showed that the space-occupying lesion of the nasal cavity originated from the ethmoid bone and was enhanced homogeneously postcontrast in all goats. Five of six goats with a mean age of 2 years, showed clinical signs of respiratory disease. The aim of this study was to describe radiography, computed tomography (CT), and magnetic resonance imaging (MRI) findings of enzootic nasal tumors in goats infected with enzootic nasal tumor viruses. 2College of Veterinary Medicine, Xinjiang Agricultural University, Urumqi, China.1Diagnostic Imaging Center of Veterinary Medicine, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.Ling-xu Li 1 Ying-jun Lv 1 Qing-yong Guo 2 Yun Liao 1 Yi-wen Guo 1 Ze-nan Su 1 Da-wei Yao 1 * De-ji Yang 1 *
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