52-year-old female with recurrent dedifferentiated endometrial carcinoma who was symptomatic with left leg pain. Axial T2 weighted MR images (A-C) of the pelvis at different levels show a multilobulated solid mass at the left pelvic sidewall/obturator space, measuring 4.6 × 3.9 cm (white arrows in A-C, red arrow in D). The mass is encasing the left distal ureter (A-B), abutting the left internal iliac vessels (yellow arrows in A-C), and abutting the left acetabulum without frank osseous invasion (red arrow in D). This patient was not deemed a suitable candidate for pelvic exenteration. The multidisciplinary tumor board’s consensus decision was to perform a systemic therapy with immunotherapy due to her comorbidities, high perioperative risk, and high-risk histology.