A case of primary gastric undifferentiated high-grade pleomorphic sarcoma diagnosed with chief complaint of fever: a case report and literature review.

Background: Undifferentiated high-grade pleomorphic sarcoma in gastrointestinal tract is extremely rare, and its prognosis is poor.

Case Presentation: An 82-year-old man visited a previous hospital complaining of fever, general fatigue, and shaking chill, for which he received antibiotics therapy. As the fever continued, he was referred to our hospital, where computed tomography and upper gastrointestinal endoscopy showed a 6-cm gastric tumor. A preoperative biopsy was consistent with a malignant mesenchymal tumor, but could not provide a definitive pathological diagnosis nor prove a cause-and-effect relationship between the chief complaint and the gastric tumor. The gastric tumor had grown to 8 cm in diameter within a month so we performed a partial gastrectomy. The pathological postoperative diagnosis was undifferentiated high-grade pleomorphic sarcoma that produced granulocyte colony-stimulating factor. The patient's fever quickly improved, and he showed a good postoperative course.

Conclusions: We herein report a case of rapidly growing, undifferentiated, high-grade pleomorphic gastric sarcoma, which presented as a chief complaint of fever.