Computed tomography enterography and 18F-FDG PET/CT features of primary signet ring cell carcinoma of the small bowel in a patient with Crohn's disease.

We report a case of a primary signet ring cell carcinoma (PSRCC) of the small bowel in a patient with long-standing Crohn's disease, describing computed tomography (CT)-enterography (CTE) and 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/CT features of this rare tumor. CTE demonstrated submucosal thickening of a long ileal segment with preserved mural stratification. PET/CT examination showed increased 18F-FDG uptake in the affected ileal loop, hypermetabolic abdominal and mediastinal lymphadenopathies, and multiple hypermetabolic bone lesions. Iliac crest osteo-medullary biopsy revealed bone marrow infiltration by "signet ring" cells with intestinal differentiation. Double-balloon enteroscopy was used to obtain biopsies that confirmed the ileal origin of the PSRCC.