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


ENDOSCOPY AND SURGERY

Two weeks later, the dog was returned to our clinic for further evaluation with endoscopy and possible surgery. The dog was premedicated with acepromazine and hydromorphone and induced with propofol. Anesthesia was maintained with isoflurane and oxygen.

The dog was placed in left lateral recumbency, and esophagoscopy was performed with a flexible endoscope, which revealed a marked right-sided protrusion into the lumen of the distal thoracic esophagus, beyond which the endoscope was unable to pass. The mass appeared to be submucosal and had a smooth covering of normal mucosa. Given the size of the mass, we decided to perform an exploratory thoracotomy, with possible resection or biopsy.

Before surgery, meloxicam (0.2 mg/kg subcutaneously), a morphine epidural (1 ml/10 kg; 15 mg/ml), and local intercostal nerve blocks with bupivacaine (1 ml/site; 2.5 mg/ml) were administered. Cefoxitin (30 mg/kg every two hours intravenously) and intravenous fluids were given intraoperatively. Intermittent positive pressure ventilation was instituted, and a right lateral thoracotomy was performed at the eighth intercostal space.


Figure 3. An intraoperative view of the esophagus after a right lateral thoracotomy shows a visible bulge in the esophageal wall.
We found a 4- to 5-cm mass in the wall of the caudal thoracic esophagus occupying about 15% to 20% of the length of the intrathoracic esophagus (Figure 3). Some consolidation of the adjacent right caudal lung was present, but no adhesions to the mass or erosion through the esophageal wall was noted. We did not resect the esophagus because we considered the risk of tension on the suture line to be excessive, given the necessary length of resection.


Figure 4. An intraoperative view of blunt dissection of the mass from the muscular layer with Metzenbaum scissors. Stay sutures are present in the adventitial and muscularis layer.
Because the mass was well-defined on palpation and appeared submucosal on endoscopy, we attempted to dissect it. A transverse incision through the adventitial layer of the esophagus was made over the lateral aspect of the mass, which was found to be dense, encapsulated, and associated with the muscular layer of the esophagus. Enucleation of the mass was performed, with easy blunt dissection from the surrounding tissues (Figure 4), leaving the inner mucosal layer of the esophagus intact. The muscular gap and adventitia were closed in one layer with 3-0 polydioxanone in an interrupted pattern (Figure 5). A chest tube was placed before the thoracic wall was closed.


Figure 5. An intraoperative view after enucleation of the mass and closure of the esophagus.
We repeated the esophagoscopy postoperatively, which revealed moderate bruising of the mucosa over the surgery site and complete removal of the extraluminal compression. Some redundant mucosa was present at the site, with mild swelling. Because the mucosal layer was intact, no gastrostomy tube was placed.

POSTOPERATIVE CARE AND HISTOLOGIC EXAMINATION RESULTS

The dog recovered from anesthesia without complications. Intravenous fluid administration was continued for 24 hours. Postoperatively, the dog was given nothing orally for 12 hours and then fed soft food for seven days. Hydromorphone (0.05 mg/kg subcutaneously) was administered as needed for 24 hours. Meloxicam was continued for five days (0.1 mg/kg orally once a day). The chest tube was removed after 24 hours. We discharged the dog after 48 hours with instructions for the owner to restrict activity for the next four weeks and return to the referring veterinarian for a recheck and suture removal in 10 days. Further instructions included providing small, frequent meals of only soft food for seven days.

Histologic examination of the mass revealed a disorganized proliferation of mature smooth muscle cells growing in an abnormal architectural arrangement, with interlacing bundles of bland spindle cells. These findings were consistent with an esophageal leiomyoma.

FOLLOW-UP

Two weeks after surgery, reexamination by the referring veterinarian at the time of suture removal revealed that the dog showed no evidence of recurrence of respiratory signs and had a normal appetite and attitude and no evidence of dysphagia. On telephone follow-up two months after surgery, the dog was clinically normal, with no episodes of dysphagia, dyspnea, or coughing. The dog's energy level and general demeanor were greatly improved. Additional follow-up was recommended if any further clinical signs were noted.


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Source: VETERINARY MEDICINE,
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