Gastric smooth muscle fleshy tumors mostly originate from the gastric muscularis propria and are relatively rare, accounting for only 20% of gastric sarcomas. There is no significant gender difference, with an average age of 54 years.

bubble_chart Pathological Changes

The tumor presents as spherical or hemispherical, primarily expanding beneath the mucous membrane and growing perpendicular to the gastric wall. It can occur singly or multiply, with some arising from malignant transformation of benign leiomyomas. It predominantly occurs in the middle and upper parts of the gastric wall, most commonly in the gastric body, followed by the gastric fundus. Based on its gross morphology, it can be classified into three types: ① Intragastric type, where the tumor is located beneath the mucous membrane and protrudes into the gastric cavity; ② Extragastric type, where the tumor is located beneath the serous membrane and protrudes outward from the gastric wall; ③ Combined intragastric and extragastric type, where the tumor is located within the gastric muscular layer, protruding both beneath the mucous membrane and the serous membrane, forming a dumbbell-shaped mass.

Half of the cases exhibit central ulceration of the tumor, and due to its rich blood supply, rupture often leads to upper gastrointestinal bleeding. The tumor can directly invade surrounding gastric tissues, frequently involving the greater omentum and retroperitoneum, and metastasizes hematogenously, most commonly to the liver, followed by the lungs. Lymphatic metastasis is uncommon.

bubble_chart Clinical Manifestations

The symptoms are nonspecific, and their timing and severity depend on the tumor's location, size, growth rate, and the presence of ulceration. More than half of the patients seek medical attention due to upper gastrointestinal bleeding, followed by upper abdominal discomfort and grade I pain. Approximately one-third of patients may have a palpable upper abdominal mass.

Findings on X-ray barium meal examination: The intragastric type shows a semicircular filling defect with smooth edges, sometimes with a central umbilicated ulcer niche; the extragastric type manifests as gastric compression with intact gastric wall mucosa and flattening of folds. Gastroscopy reveals the characteristics of a submucosal mass, and if an ulcer is present, biopsy from this site facilitates definitive diagnosis.

Differentiation from benign leiomyoma is necessary. Generally, tumors exceeding 3 cm in diameter should be considered malignant. If biopsy shows cellular pleomorphism and active mitosis, malignancy should be strongly suspected.

bubble_chart Treatment Measures

Gastric smooth muscle fleshy tumors are not sensitive to radiation or chemotherapy, and the primary treatment is surgical resection, with the same scope of resection as stomach cancer surgery. The 5-year survival rate after resection is 35–50%.