Veterinary Society of
Surgical Oncology

General Considerations

  • leiomyoma is common in very old dogs and is the 2nd most common gastric tumor in dogs
  • mean age 15 years with 82% prevalence in 17-18-year-old Beagles
  • discrete solitary lesions (usually pedunculated) in the cardia or gastroesophageal junction causing mass effect
  • ulceration is uncommon

Clinical Signs

  • clinical signs are caused by gastric outflow obstruction, altered motility, or chronic blood loss secondary to tumor necrosis and ulceration
  • progressive vomiting is common and may contain fresh or digested blood
  • weight loss may be caused by poor digestion, protein malnutrition, or cancer cachexia

Laboratory Tests

  • laboratory tests and survey radiographs are usually unrewarding
  • leiomyoma and leiomyosarcoma have been associated with paraneoplastic hypoglycemia
  • microcytic hypochromic anemia is common with chronic blood loss and occult blood may be detected in feces
  • increased liver enzymes may be seen with hepatic metastasis or obstruction of the common bile duct

Imaging

Radiographs

  • positive- or double-contrast radiographs: gastric tumors can appear as a mass effect, ulcer crater, delayed gastric emptying with poor motility, and delayed adherence of contrast material to an ulcerated tumor

Ultrasonography

  • ultrasonographic findings include transmural thickening of the gastric wall with loss or altered layering (poor echogenic outer and inner lining with hyperechoic central zone)
  • other findings include tumor location, ulceration, extension through gastric wall, and lymphadenopathy
  • benign lesions tend to be either pedunculated or well circumscribed with gastric leiomyoma commonly located in the cardia

Endoscopy

  • gastroscopy allows direct visualization and guided biopsy
  • several biopsies should be performed as superficial ulceration, necrosis, and inflammation is common
  • submucosal masses are difficult to biopsy and false-negative results are common

Other Imaging Techniques

  • CT and MRI

TREATMENT

Surgery

General Considerations

  • surgery is recommended for gastric leiomyoma and leiomyosarcoma, but complicated by advanced stage at presentation, frequent metastasis, difficult access, and debilitated animal
  • lymph node metastasis is variable and all abdominal lymph node should be evaluated for staging purposes
  • curative resection should be attempted if disease is localized to the stomach
  • surgical techniques: Billroth I or II or palliative bypass procedures
  • Billroth I or II provides immediate relief of gastric outflow obstruction and clinical improvement in early postoperative period
  • Billroth II (partial gastrectomy and gastrojejunostomy) or complete gastrectomy (with biliary by-pass) are very extensive surgeries with high morbidity and minimal survival advantage
  • partial gastrectomy preferred in humans due to better nutritional status and quality of life and radical gastrectomy does not improve survival time
  • palliative gastrojejunostomy for inoperable or metastatic lesions but associated with significant morbidity including anastomotic ulcers

Leiomyoma

  • gastrotomy via exploratory ventral midline or lateral intercostal thoracotomy approach
  • gastrotomy and submucosal resection recommended with minimal risk of contamination, hemorrhage, or stricture, and good tumor control

Chemotherapy

  • no known effective chemotherapy agents for gastric leiomyosarcoma

Prognosis

  • prognosis depends on surgical excision, tumor type and grade, and presence of metastatic lesions
  • gastric leiomyosarcoma: MST 12.0-21.3 months, with 1-year survival rate 75% and 2-year survival rate 66%
  • 54% metastatic rate, but metastasis is not a poor prognostic factor with a MST 21.7 months
  • leiomyoma an excellent prognosis following surgical resection

GASTRIC LEIOMYOMA AND LEIOMYOSARCOMA

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