Case summary A 6-year-old male domestic shorthair cat presented with frequent food regurgitation and dysphagia. Plain thoracic radiographs revealed a calcified mass overlying the topography of the mediastinum, as well as dilation of the cervical portion of the esophagus due to an accumulation of food. Endoscopic examination showed a severe extraluminal esophageal stricture at the mediastinum entrance. Surgery and a gastric tube were declined by the cat’s owner, with palliative support preferred. However, 1 year later, the cat presented with severe cachexia, dysphagia, salivation, dehydration and inspiratory dyspnea. Thoracic computed tomography was performed to evaluate the possibility of surgical resection. A mass of bone density originating in the second left rib was observed. The mass did not appear to have invaded adjacent structures but marked compression of the mediastinal structures was observed. Surgical resection was performed and a prosthetic mesh was used to reconstruct the thoracic wall. Transient Horner’s syndrome developed in the left eye postoperatively, and was resolved within 4 weeks. Histopathology revealed a benign osteoma. Thirty-two months after surgery, the cat was well and free of disease. Relevance and novel information Rib tumors should be included in a differential diagnosis in cats with extraluminal esophageal stricture. CT should be performed for treatment planning. Surgical treatment was curative in this case.