Gastric High-Risk Gist and Retroperitoneal Liposarcoma – A Challenging Combination of Two Mesenchymal Tumor Lesions with Regard to Diagnosis and Treatment

Both gastrointestinal stromal tumors (GIST) and liposarcoma originate from mesenchymal tissue. Their coincidence requires a specific expertise in the diagnostic and therapeutic management. An unusual exemplary case is described representing a 47-year old female patient with a gastric GIST and a monstrous retroperitoneal liposarcoma with infiltration of the left kidney. The gastric tumor lesion was removed with a tangential resection of the gastric wall; the retroperitoneal tumor lesion was resected including the left kidney. Both tumors were resected with no macroscopic tumor residual. The technically difficult surgical intervention did not show any postoperative complication, and the postoperative course was also uneventful. The complete tumor resection is the treatment of choice in mesenchymal tumors (aim: R0). Depending on histologic tumor classification, resection status and tumor sensitivity, a subsequent radiation and/or chemotherapy is necessary, which allowed to achieve a postoperative tumor-free survival of 6 years including a good quality of life.