Bronchoscopic Debulking of Tracheal Carcinoma in 3 Cats using a Wire Snare

Case 1: A 10-year-old spayed female domestic short-haired cat was presented to the University of California Veterinary Medical Teaching Hospital (UCD VMTH) for a 1-month history of persistent respiratory difficulty that was nonresponsive to prednisolone and furosemide prescribed by the local veterinarian. On physical examination, the cat was quiet and alert with a body condition score of 8/9. The cat sat with elbows abducted and demonstrated marked abdominal effort on both inspiration and expiration. High-pitched stridor was auscultated over the trachea and referred airway sounds were heard over all of the thorax. The remainder of the physical examination was within normal limits. Cervical and thoracic radiographs identified an intratracheal soft tissue mass at the level of the third rib. The remainder of thoracic radiographs were considered within normal limits, and an abdominal ultrasound examination with hepatic and splenic aspirates were unremarkable. The cat was anesthetized and tracheoscopy performed with a 5 mm × 55 cm fiberoptic endoscope.a A broad-based tracheal mass was noted 3 cm proximal to the carina and occluded approximately 90% of the airway lumen (Fig 1). Multiple biopsy samples were collected with spiked-cup biopsy forcepsb and airway hemorrhage was controlled by intermittent suction. The obstruction was too far distal to bypass by a tracheostomy, and because of concerns about anesthetic recovery, attempts were made to debulk the mass. Additional biopsy samples were obtained around the base of the obstruction to undermine the mass. A 1.8 mm 2-wire snareb was passed through the 2 mm biopsy channel of the endoscope, and the snare was twisted toward the wall of the trachea to encircle and entrap the mass. The instrument was retracted into the endoscope to sever the neoplasm from the tracheal wall, and the endoscope was withdrawn with the mass attached to the snare. Using this approach, tracheal luminal diameter was restored to approximately 95% of normal (Fig 2). Bronchoscopy was completed with a 3.8 mm × 55 cm video-endoscopec and identified a second mass occluding approximately 60% of a bronchial opening in the right caudal lung lobe (Fig 3) and this mass was removed with spiked-cup biopsy forceps.b Histopathology of both masses was consistent with a diagnosis of well-differentiated mucinous adenocarcinoma. Bronchoscopic image of a tracheal carcinoma in cat 1. Bronchoscopic view of the trachea after the tracheal carcinoma had been debulked and hemorrhage had been suctioned from the airway in cat 1. Bronchoscopic image of a carcinoma identified in the right caudal lobar bronchus of cat 1. Immediate improvement in respiratory effort was noted on the morning after the procedure. At 2-month re-evaluation, the cat was eupneic with a respiratory rate of 40 breaths/min. Cervicothoracic radiographs disclosed mild thickening within the trachea at the site of mass removal. Five months later, increased sounds were noted over the trachea on inspiration and expiration, and a high-pitched whistling sound was detected over the trachea on expiration. Radiographs identified regrowth of the mass at the site of prior removal with occlusion of approximately one third of the tracheal luminal diameter. Six months after the mass was debulked, increasing respiratory effort was noted. Repeat endoscopy or placement of an intratracheal stent was declined, and the cat was euthanized. No necropsy was performed. Case 2: A 16-year-old castrated male domestic medium-haired cat was presented to the UCD VMTH with a 7-week history of wheezing and labored breathing that was nonresponsive to prednisone or amoxicillin-clavulanic acid.d On physical examination, there was marked abdominal effort on inspiration and expiration. Increased breath sounds were auscultated over the extrathoracic trachea and all lung fields. Cervical radiographs showed a narrowing of the trachea in the extrathoracic region compatible with an intramural tracheal lesion. Ultrasound examination showed a mass within the tracheal wall. The cat was premedicated with oxymorphone, and induced and maintained on isoflurane with oxygen support provided by jet ventilation. Tracheoscopy was performed with a 5 mm × 55 cm fiberoptic endoscope.a A proliferative, broad-based lobular mass was evident approximately 3 cm distal to the larynx and extending 2 cm down the trachea. The mass appeared to encompass 7–8 tracheal rings. The mass was biopsied multiple times with the endoscopic cup biopsy forceps followed by removal of approximately 80% of the mass lesion with the endoscopic wire snare as described for case 1 (Fig 4). Minimal bleeding occurred and was controlled with suction. Histopathology was consistent with a tracheal squamous cell carcinoma. Respiration was improved after the procedure, and the cat was discharged. The cat, however, was euthanized 4–6 weeks after discharge for worsening respiratory distress, and no necropsy was performed. The endotracheal squamous cell carcinoma was entrapped by the wire snare and removed from cat 2. Image was taken at withdrawal from the larynx. Case 3: A 6-year-old spayed female Egyptian Mau cat presented for evaluation of inspiratory respiratory difficulty. Physical examination disclosed inspiratory stridor, and cervical and thoracic radiographs indicated an intraluminal mass in the distal cervical trachea. The cat was anesthetized and supported with jet ventilation during tracheoscopy with a 5 mm × 55 cm flexible fiberoptic endoscope.a A 2.5–3 cm broad-based mass was identified at the thoracic inlet and obstructed approximately 75% of the tracheal lumen. Multiple biopsy samples were obtained with cup biopsy forceps to debulk the mass, and the cat was recovered from anesthesia. Histopathology was consistent with adenocarcinoma. Five weeks later, the cat was eupneic with a respiratory rate of 44 breaths/min and normal upper airway auscultation. Computed tomography of the cervical region identified a sessile mass involving 50% of the tracheal circumference just cranial to the thoracic inlet. A ventral midline surgical approach was used to isolate the trachea and 8 tracheal rings were resected. An infiltrative adenocarcinoma was documented with neoplastic cells extending to the surgical margins. The owners declined follow-up radiation therapy. Twenty-six months later, the cat represented for increased respiratory noises. Stridor was present on physical examination, and cervical radiographs confirmed recurrence of the tracheal mass at the level of the thoracic inlet where the resection and anastomosis had been performed (Fig 5). The cat was anesthetized and supported with jet ventilation for tracheoscopic debulking of the mass. Tracheoscopy was performed with a 5 mm × 55 cm fiberoptic endoscope,a and the mass was debulked with biopsy forceps and the wire snare as described for case 1. At re-evaluation 1 month later, mild end inspiratory stridor was auscultated. Results of cervical radiographs were similar to those taken immediately after debulking. Phone conversation with the owner 3 months later indicated that the cat was stable. Nine months after tracheoscopic debulking of the neoplasm and 35 months after the initial diagnosis, the cat developed acute respiratory distress and was euthanized by the local veterinarian. No necropsy was performed. Lateral neck radiograph from cat 3 showing a broad based mass within the tracheal lumen at the level of the thoracic inlet. Tracheal neoplasia is uncommon in the cat, with lymphoma, squamous cell carcinoma, and adenocarcinoma reported most frequently.1 Clinical signs often are indicative of airway obstruction, with respiratory difficulty reported most commonly. Coughing, loud breathing, and dysphagia also can be seen. Standard care for lymphoma includes chemotherapy, radiation therapy, or a combination of these, and long-term control of clinical signs has been reported.2 Optimal treatment for other types of tracheal malignancies in human medicine involves resection and anastomosis,3 and this likely would be true for cats also. A review of all cases of tracheal neoplasia in cats seen at the UCD VMTH over the time period from 2004 to 2009 identified 6 cases, with adenocarcinoma (n=3) diagnosed most commonly. The remaining 3 cats had carcinoma, squamous cell carcinoma, and plasmacytoma. One cat with adenocarcinoma was treated with tracheal resection and anastomosis but was euthanized 4 days postoperatively after suffering cardiac arrest twice and being placed on a ventilator. The cat with complex carcinoma had obstruction of the left mainstem bronchus and collapse of left lung lobes, and was lost to follow-up after the diagnosis was made. The cat with plasmacytoma was treated with melphalan and steroids and was euthanized after 6 weeks because of worsening respiratory difficulty. Interestingly, no reports of tracheal lymphoma were identified in our hospital population of cats over the aforementioned time period. There is a paucity of information on the comparative response and survival times of cats with tracheal neoplasms. A retrospective study evaluating outcome in 27 cats with both benign inflammatory and neoplastic laryngeal, laryngotracheal, and tracheal masses reported a median survival time of 5 days (range, 1–370 days) for cats with inflammatory obstructive masses, and 15.5 days (range, 1–1,109 days) for cats with neoplastic masses.1 Therapies used in this group of cats ranged from none to single or multimodal therapy including medical and surgical options, and responses for tumors at all sites were grouped together. It is likely that optimal therapy for nonlymphomatous tracheal neoplasia is resection and anastomosis, but the extent and location of the tracheal neoplasm dictates whether it will be amenable to surgical resection and anastomosis. Preoperative computed tomography with contrast is optimal to determine the extent of disease and screen the thorax for metastasis. Preparation should be made for immediate surgical intervention or bronchoscopic debulking of the mass at the time of initial diagnostic evaluation because of the difficulty in recovering cats from anesthesia when airway obstruction is present. In addition, the tumor may be too distal in the airway to bypass with a tracheostomy, and tracheostomies are difficult to manage in cats.4 Intrathoracic tracheal neoplasms require a more invasive surgical approach than do neoplasms located in the cervical region with the potential for substantial surgical and postoperative morbidity and mortality. In the cats described here, tracheal obstruction occurred in the distal cervical or intrathoracic region in each case, and bronchoscopic reduction of the mass prevented the need for thoracotomy. In our case series, all 3 intratracheal neoplasms were debulked by undermining the mass at its base with biopsy forceps, and then entrapping the mass with the 2-wire snare to sever it from its attachment to the tracheal wall. In the cats reported here, this technique markedly increased tracheal diameter and resulted in substantial improvement in clinical signs. This technique is similar to that described for safe and effective treatment of humans with benign tracheal masses, where a laser is used to undermine the mass followed by removal with an endoscopic snare.5 Removal of a mass by laser or electrocautery would likely be an effective technique in the cat and would have the benefit of controlling airway hemorrhage, although access to appropriate equipment could limit implementation of this methodology. In the dog, bronchoscopic reduction of a mass obstructing the right mainstem bronchus has been described, but the dog lived only 1 month after the procedure.6 Importantly, cats treated in this manner had prolonged survival without need for continued medical therapy. The cat with the shortest survival time (case 2) was diagnosed with squamous cell carcinoma rather than adenocarcinoma, but it is not possible to generalize regarding response to therapy with such a small case series. Interestingly, the cat with the longest survival time (9 months) had previously undergone tracheal resection and anastomosis that was followed by bronchoscopic debulking when the mass recurred. This finding suggests that substantial palliation of signs can be achieved when a slow-growing tumor is removed by debulking and surgical therapy is not an option. Another palliative option considered in case 1 to manage regrowth of the intratracheal neoplasm was placement of an intraluminal tracheal stent, either alone or after debulking of the mass. Stent placement has successfully palliated signs of airway obstruction in cats with benign and malignant tracheal lesions, but metastatic disease resulted in euthanasia 6 weeks after stent placement in the sole cat with malignancy.7 Interestingly, case 1 reported here had metastatic disease at the time of removal of the tracheal lesion yet still survived 5 months with simple debulking of the obstructive mass within the trachea. Bronchoscopic debulking of tracheal masses is a relatively simple, noninvasive, and safe means of palliating tracheal tumors in cats. Major complications that could be encountered with bronchoscopic debulking include excessive hemorrhage and tracheal perforation. No clinically important complications were encountered in our case series, and none of the 3 cats required placement of a temporary tracheostomy tube. aOlympus P20D, Olympus Corporation, Melville, NY bOlympus Endoscopic Instruments, Olympus Corporation cOlympus BF3C160, Olympus Corporation dAmoxicillin-clavulanic acid, Pfizer Animal Health, New York, NY