Rectal adenocarcinoma coexisting with incidentally found microscopic gastrointestinal stromal tumor: A case report

RATIONALE: Adenocarcinoma coexists with adjacent microscopic gastrointestinal stromal tumor (micro-GIST) is rare, especially in the rectum, where the gastrointestinal stromal tumors (GISTs) have the lower incidence rate. It is easy to ignore the concurrent micro-GIST due to the untypical symptoms. PATIENT CONCERNS: A 77-year-old male patient suffered from lower abdominal pain for 20 days and presented with per rectal bleeding for 10 days. He had the medical history of hypertension and diabetes for more than 25 years. DIAGNOSES: Endoscopy revealed that the patient had rectum adenocarcinoma and multiple rectum polyps. Besides, the gastrointestinal stromal tumor was diagnosed by the pathologist. INTERVENTIONS: The patient underwent surgery of laparoscopic rectum resection and prophylactic ileostomy and took 6 courses of Capecitabine tablets orally. OUTCOMES: One year after surgery, the patient had no local relapse by the CT scan. However, not long after the CT examination, he died of cardiovascular disease. LESSONS: Although micro-GIST may be noninvasive and asymptomatic, it may have the potential for transforming to malignancies. More attention should be paid to the patients diagnosed with gastrointestinal malignancy coexisting with micro-GIST.