A case of gastrointestinal stromal tumor metastasized to the left ventricular myocardium.

BACKGROUND: Gastrointestinal stromal tumors (GISTs), which are the most common soft tissue tumors of the gastrointestinal tract, originate from Cajal interneurons. The main metastatic sites of GISTs are the liver and intra-abdominal cavity, and metastasis to the heart is rare.

CASE PRESENTATION: The patient was a 78-year-old man who was diagnosed with a rectal GIST 20 years previously. Since then, he had undergone repeated operations for metastasis. A follow-up thoracoabdominal computed tomography scan 4 months prior to the operation revealed GIST metastasis to the left ventricular myocardium. The patient wanted the tumor removed and consequently underwent an operation. The surgical findings showed a 3-cm × 3-cm mass in the lateral wall of the left ventricle. The mass was resected from the left ventricular wall in the shape of a tear drop. The left ventricular cavity was closed with a 4-0 polypropylene mattress suture and continuous suture. Postoperative histopathological findings showed nodular tumor growth consisting of bundles of spindle-shaped cells in the myocardium. The margins were negative. Immunostaining showed c-KIT (CD17) positivity and CD34 positivity, consistent with GIST metastasis.

CONCLUSIONS: This case involved GIST metastasis to the heart muscle, which has rarely been reported worldwide.