Primary gastric leiomyosarcoma presenting as a giant polyp

Digestive pseuodpolyposis as a form of presentation of digestive metastases of primary gastric leiomyosarcoma

A 71-year-old male was diagnosed with gastric leiomyosarcoma in 2020 after biopsies of an ulcerated gastric lesion. Despite oncological treatment, he presented bone, liver and lung progression. Fourth line treatment with Pazopanib was started in 2022 with no evidence of intestinal or peritoneal metastases. He was attended in the Emergency Department in February 2023 due to symptoms of gastrointestinal bleeding with clinical and analytical repercussion with hemoglobin 5.8g/dl. Initially he presented hematemesis and subsequently hematochezia. An upper and lower endoscopic study was performed, revealing multiple sessile polypoid lesions with an irregular mucosal pattern of between 5-30 mm distributed throughout all explored sections at the gastric, duodenal and colic mucosal; some of them ulcerated with fibrin deposits on the surface and signs of recent hemostasis. The histological study demonstrated infiltration by spindle-shaped mesenchymal cells with atypical nuclei, a Ki-67 proliferation index >80%, and an immunohistochemical profile consistent with digestive metastases of primary gastric leiomyosarcoma. CT scan was performed confirming tumor progression with pulmonary, digestive, hepatic, bone, muscle and peritoneal dissemination of gastric leiomyosarcoma.