RESUMO
Background: Tracheal tumors are rare and may cause obstruction of the trachea. The neoplasms most commonly diagnosed in cats are lymphosarcoma, squamous cell carcinomas and adenocarcinomas. Surgical resection may provide a clinical cure for small, benign and localized tumors. For malignant neoplasia, surgery is usually palliative. Tracheal segment excision is an invasive procedure, particularly when the intrathoracic trachea is involved, and this increases the risk of stenosis, surgical suture dehiscence, necrosis and pneumothorax. Intraluminal tracheal stents have been used in dogs with tracheobronchomalacia, presenting a feasible alternative to surgery for the treatment of tracheal lumen obstruction. Case: A 11-year-old male mixed-breed cat was referred to the Veterinary Hospital of the Federal University of Rio Grande do Sul (HCV-UFRGS) with a history of appetite loss, wasting and progressive inspiratory dyspnea, for the last 30 days. The cat presenting with oral breathing. Radiography of the lateral thorax shown a radiopaque area, 1cm in diameter, superimposed in the tracheal region, close to the carina cartilage, at the fourth intercostal space. A tracheoscopy confirmed the diagnosis of tracheal neoplasia, which was identified as an adenocarcinoma by biopsy and histopathology. Given that surgical resection may result in significant morbidity and consequent mortality, the owner chose a palliative treatment without adjuvant therapy for adenocarcinoma until acquisition of the stent, with partial resection of the tumor performed during tracheoscopy. This procedure was performed twice at an interval of three months. After the first endoscopic examination, the patient regained weight and normal behavior. Three months after the second tracheoscopy, signs of labored breathing recurred. At this point, the obstruction was treated with implantation of an intratracheal stent. A nitinol biliary stent, 35 mm in length, 8 mm in diameter, was applied during tracheoscopy without fluoroscopy aid. The cat received postoperative treatment with dexamethasone 0.25 mg.kg¹ SID for seven days. The patient showed immediate clinical improvement in dyspnea, but retained an episodic cough. After six months, the cat suffered a relapse of dyspnea. Radiographic examination revealed a large area of radiopacity in the region of the tracheal stent, suggesting an increase in size of the tumor, and possible metastasis in the lung parenchyma. The patient underwent repeat tracheoscopy, and almost complete obstruction of the tracheal lumen was found. The cat died during this procedure. Post-mortem examination was requested, which confirmed tracheal obstruction resulting from growth of the tumor, and pulmonary metastasis. Discussion: There are few reports of tracheal neoplasms in cats, because they are uncommon. The diagnosis was based on radiography, tracheoscopy and incisional biopsy. Treatment with surgery involves high morbidity and mortality. For this reason we chose the use of a tracheal stent, although palliative in cases of cancer. Stents are frequently used in humans with malignant tracheal obstruction, but the few reports in the veterinary literature, are focused on dogs presenting with tracheobronchomalacia. In cats, a few cases of tracheal stenosis and tumors have been treated experimentally with stents, which have shown success in reestablishing an airway. In previous reports, the technique has always been carried out with the aid of fluoroscopy. The application of the stent using tracheoscopy alone was efficient. The patient in this report suvived for one year since it diagnosed before near-total obstruction of the trachea occurred. Therefore this was a palliative measure, which allowed the patient a good quality of life while receiving adjuvant therapy when possible or necessary.