EXPRESS: Bronchoscopic cryotherapy for biopsy and debulking of tracheal myxosarcoma in a cat

Case summary A 10-year-old castrated male domestic shorthair cat presented with stertor and severe respiratory distress caused by intratracheal masses occluding the majority of the tracheal lumen. Conventional endoscopic forceps biopsy yielded small tissue fragments, which were insufficient for a definitive histopathologic diagnosis. Given the perceived high risk of tracheal resection and anastomosis, bronchoscopic cryotherapy with a 1.1-mm flexible cryoprobe was performed for cryobiopsy and cryo-debulking. The masses occluded 80–90% of the lumen and were completely removed with cryotherapy, with immediate clinical improvement and decreased airway resistance (279 to 31 cmH₂O/l/s). Hemorrhage was mild and controllable, and recovery was uneventful. Histopathology revealed tracheal myxosarcoma, a neoplasm not previously described in the feline trachea. The cat remained free of clinical signs for 7 weeks, after which clinical signs recurred with radiographic evidence of regrowth. Pulmonary function testing suggested no substantial ventilatory compromise compared with pre-procedure findings, so continued observation was chosen given the early recurrence. Three months after the initial intervention, bronchoscopy was repeated due to gradually worsening clinical signs and confirmed tumor regrowth occluding approximately 50% of the lumen. A second cryotherapy session again achieved complete debulking and rapid resolution of signs. Relevance and novel information This report documents the first described tracheal myxosarcoma in a cat and demonstrates that bronchoscopic cryobiopsy can overcome limitations of forceps biopsy while providing concurrent, airway-sparing palliative debulking. Bronchoscopic cryotherapy could serve as a feasible, minimally invasive diagnostic and therapeutic intervention for intraluminal tracheal masses in cats.