+ 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
- 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