Abstract
BACKGROUND: Ulcerative colitis (UC) is a chronic inflammatory bowel disease treated with immunosuppressants to control inflammation. Drugs like azathioprine (AZA) and anti-tumor necrosis factor agents increase the risk of extraintestinal malignancies. However, no association has been established between these therapies and endometrial stromal sarcoma. This report presents a rare case of endometrial stromal sarcoma in a patient with UC undergoing immunosuppressive treatment and includes a literature review to explore any possible correlation between the disease, the therapies used, and the development of this rare tumor. CASE SUMMARY: Female, 49 years old, with UC pancolitis extension since 2017. She used aminosalicylates and AZA with non-response. She started infliximab and AZA combination therapy in 2020, with optimization in 2021 due to endoscopic activity. In the same year, the patient presented to the emergency room with ascitis and underwent diagnostic paracentesis, which showed serum-ascites albumin gradient < 1.1 g/dL, absence of neoplastic cells, and abdominal and pelvic tomography reported a hypoechoic nodular lesion in the posterior wall of the uterus and elevated carbohydrate antigen 125. Given the suspicion of neoplasia, the suspension of immunosuppressive therapy was indicated. The patient underwent a total abdominal hysterectomy and bilateral salpingo-oophorectomy, and the pathological result reported low-grade endometrial sarcoma. It was decided to introduce vedolizumab for the management of UC; however, even after induction therapy, intense clinical and endoscopic disease activity was maintained, with total proctocolectomy being indicated due to clinical refractoriness and a history of neoplasia. CONCLUSION: Patients with inflammatory bowel disease have a higher risk of cancer due to inflammation or treatment. Proper screening with multidisciplinary care can improve outcomes.