Concomitant occurrence of primary gastric sarcomatoid carcinoma and giant gastrointestinal stromal tumor: a case report and literature review

Background: Gastric sarcomatoid carcinoma (GSC) is a rare and aggressive malignancy, with only 16 cases reported in the English literature. Herein, we report an exceptionally rare case of synchronous primary GSC and gastrointestinal stromal tumor (GIST), a dual-tumor entity that has rarely been characterized in the existing literature. Case presentation: The patient was a 60-year-old man with GSC and GIST of the stomach who presented with dark stools and fatigue. Computed tomography (CT) imaging revealed gastric wall thickening and a large solid cystic mass adjacent to the gastric wall. Gastroscopic biopsy revealed a poorly differentiated carcinoma at the antrum-body junction. The patient underwent radical distal gastrectomy. Postoperative pathology indicated a sarcomatoid carcinoma (SC) of the greater curvature of the gastric body and an extraserous GIST. Postoperatively, adjuvant imatinib was administered. Two months later, multiple liver metastases were detected and confirmed by biopsy to be GSC metastases. Conclusions: This report describes a rare concomitant occurrence of GSC and GIST, with significant diagnostic challenges. In complex gastric tumors, vigilance for such a rare combination is essential, necessitating a thorough pathological evaluation for accurate diagnosis and individualized treatment. A misdiagnosis can lead to severe consequences.