Case Presentation

A 22-year-old female, previously healthy, without alcohol or smoking habits, was referred to our hospital after an emergency appendectomy in October 2019 at Centro Hospitalar da Cova da Beira (CHCB). During appendectomy, surgeons found a retroperitoneal mass. There was no previous knowledge of this retroperitoneal mass, and the patient had never had any abdominal symptoms before. Abdominal computed tomography was initially performed to better characterize the mass, followed by magnetic resonance. What is the most probable diagnosis?

Figure 1: Axial soft tissue window, 1.2 mm slice thickness, non-enhanced CT (A), and contrast enhanced CT (B). 

Figure 2: coronal soft tissue window, non-enhanced CT (A), and contrast-enhanced CT (B). 

Figure 3: axial T1 weighted (A), axial T1 weighted contrast-enhanced (B), and T2 FS weighted (C) MRI