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