A challenging case: Esophageal leiomyoma in a dog - Veterinary Medicine
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A challenging case: Esophageal leiomyoma in a dog
These clinicians discovered that a senior dog's respiratory problems were caused by a benign but sizable esophageal tumor.


VETERINARY MEDICINE


Treatment

Surgical resection of leiomyomas may be curative. While extensive reports are available in the human literature, reports on treatment in dogs are sparse. One study in three dogs with leiomyomas at the gastroesophageal junction treated by enucleation reported no recurrence for 8 to 18 months.13 Gastric leiomyomas have been successfully removed by both partial gastrectomy and mass dissection alone.14,15 Colorectal leiomyomas in seven dogs were treated with enucleation of the mass via the serosal or mucosal surface, with no recurrences.16

In people with esophageal leiomyomas, surgical removal is recommended if unremitting signs, a progressive increase in tumor size, or any mucosal ulceration exists.6 Conservative management and periodic endoscopy are often recommended for asymptomatic patients with tumors less than 3 cm,12 but sarcomatous transformation has been described.17

In people, standard therapy involves a lateral thoracotomy, with extramucosal enucleation of the mass. Enucleation involves separating the overlying adventitia and muscle longitudinally and performing blunt dissection, avoiding damage to the submucosa and mucosal layers.6,17 If necessary, visualization can be improved by injecting saline solution under the serosal and muscular layer to separate the planes and create a cushion between the lesion and the muscle layer.12 It is important to repair the mucosa if it is injured during dissection, as well as to close the myotomy after mass removal. Postoperative diverticula have been reported in people if the muscle layer is not reapposed.6 Tumors up to 8 cm are easily enucleated in people. Those greater than 8 cm can be removed, but the remaining muscle defect may be too large to easily close.6 If the tumor has a broad base and is tightly adherent, complete removal may not be possible by enucleation.7 Without complete removal, recurrence is likely, so debulking alone is unlikely to provide long-term relief.

Esophageal resection may be required in about 10% of people. Human mortality rates are reported from 0% to 1.3% for leiomyomas. Most patients have complete resolution of symptoms, with 89% to 94% of patients symptom-free five years later. Complications after leiomyoma enucleation in people are rare, but include diverticula, fistula, reflux esophagitis, stenosis, ulceration, and, rarely, recurrence.6 The incidence of esophagitis can increase after excision because of decreased propulsive activity and acid clearing mechanism impairment, especially in patients with a previous history of reflux. All of these complications should be considered as possible postoperative complications in dogs.

In general, esophageal surgery is prone to serious complications, including infection, regurgitation, esophagitis, dehiscence, fistula formation, stricture, and disease recurrence. The high complication rate associated with esophageal surgery has been attributed to many factors, including esophageal movement during swallowing, high wound tension, lack of a serosal layer as present in the small and large intestinal tract and omentum to help provide an early seal and promote vascularization to a repair, and the presence of a segmental blood supply to the esophagus.18,19 After esophageal surgery, particularly in cases involving resection and anastomosis or mucosal penetration or damage, use of a gastrostomy tube is recommended to decrease the amount of motion occurring at the surgical site and facilitate mucosal healing.20

In this case, esophageal resection and anastomosis were initially considered but would have required resecting 6 cm of thoracic esophagus to provide a 1-cm margin around the neoplasm. Experimentally, resection and primary anastomosis of up to 20% of the cervical esophagus and 50% of the thoracic esophagus have been reported in dogs.21 Clinically, resection of more than 3 to 5 cm increases the risk of dehiscence.20 Circumferential partial myotomy can reduce anastomotic tension and decrease the risk of dehiscence in dogs.22 Partial esophagectomy has also been reported for malignant esophageal neoplasms in dogs, with resection of the mass and then longitudinal closure of the resulting defect.3


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Source: VETERINARY MEDICINE,
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