Umbilical Endometriosis Mimicking Malignancy on 18F-FDG PET/CT

Umbilical endometriosis is a rare event. A 44-year-old woman complained of a palpable abdominal mass with bloody secretion and chronic abdominal pain for 2 months. 18 F-FDG PET/CT images demonstrated multiple foci of increased tracer uptake indicating malignant tumor with metastases in the region of umbilicus and lower segment of the esophagus. Unexpectedly, the subsequent histology and immunohistochemistry of the umbilical lesion demonstrated endometriosis.