Abstract
Mucinous adenocarcinoma of the urachal remnant is a nonurothelial malignancy that
may be asymptomatic until locally advanced or metastatic. We describe a 37-year-old
woman with invasive ductal breast carcinoma who underwent 18Fluorine-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) computed tomography (CT) demonstrating a
non-FDG avid pelvic mass, initially suspected to represent a pedunculated uterine
fibroid. Magnetic resonance imaging revealed a mixed solid-cystic mass separate from
the uterus, suspicious for urachal neoplasm, confirmed as mucinous adenocarcinoma
on histopathology. Urachal tumors may not be FDG-avid and represent a potential pitfall
on FDG PET/CT.
Keywords
18Fluorine-fluorodeoxyglucose - mucinous neoplasm - positron emission tomography/computed
tomography - urachal adenocarcinoma