Academy of Medical Sciences of I.R. Iran Archives of Iranian Medicine 1029-2977 27 3 2024 03 01 Synchronous Double Primary Angiosarcoma Originating from the Stomach and Rectum: A Case Report and a Literature Review 168 173 10.34172/aim.2024.25 EN Tanju Kapagan https://orcid.org/0000-0001-9381-1934 Nilufer Bulut https://orcid.org/0000-0002-2406-1946 Gokmen Umut Erdem https://orcid.org/0000-0002-3375-9465 Suleyman Yıldırım https://orcid.org/0000-0002-2607-6738 Zeynep Betul Erdem https://orcid.org/0000-0002-0840-4689 Halil Sahin https://orcid.org/0000-0002-2718-0326 Journal Article 10.34172/aim.2024.25 2024 01 31 2024 02 12 Angiosarcomas originating from the gastrointestinal tract are rare but highly aggressive tumors with poor prognosis. These tumors can be misdiagnosed as benign and malignant gastrointestinal tract lesions. The definitive histological diagnosis of angiosarcomasis made by pathologists based on immunohistochemical analysis demonstrating cluster of differentiation 31 (CD31), factor VIII-related antigen (FVIIIRAg), erythroblast transformation specific related gene (ERG), and cluster of differentiation 34 (CD34). Angiosarcomas are treated with a single or multimodality approach that may include resection, radiotherapy, chemotherapy, and palliative care, depending on the stage of disease and the condition of the patient. No matter the treatment option, metastasis and death rates are substantially highin patients with angiosarcoma. In this context, a 59-year-old male with synchronous double primary angiosarcoma arising from the gastric and rectum who presented with the complaint of abdominal pain and distention to the outpatient clinic is presented in this case report, along with a brief literature review.