Small bowel invagination caused by intestinal melanoma metastasis - Unsuspected diagnosis by FDG-PET/CT imaging

FDG-PET/CT was performed for restaging in a 46-year-old woman with a cutaneous malignant melanoma of the leg resected 4 years previously and an increasing S-100 tumor marker. Besides multiple focal lesions with increased FDG accumulation in the lungs, bone and soft tissue FDG-PET/CT images demonstrated focal FDG activity in the lower abdomen. With the CT information, the lesion could be localized in the small bowel. CT images additionally demonstrated a "crescent-in-doughnut sign" and "sandwich sign"-typical CT signs for an invagination. Four hours after the PET/CT scan, the patient developed obstructive bowel symptoms, which were treated conservatively because of the palliative tumor situation. The patient died 4 months later. © 2007 Lippincott Williams & Wilkins, Inc.