[A case of jejunal ectopic pancreatic cancer: the diagnostic usefulness of MRI].

A 70-year-old man was referred to our hospital because of elevated CA19-9. Magnetic resonance imaging revealed a jejunal tumor having duct and retention cyst-like structures, which suggested ectopic pancreatic cancer. We resected that part of the jejunum and the lymph nodes around the tumor. Pathological examination revealed an adenocarcinoma originating from a Heinrich type I ectopic pancreas in the jejunum. Adjuvant chemotherapy with gemcitabine was performed for half a year. After 8 months, CA19-9 remained elevated, and liver metastasis occurred. We began treatment with tegafur/gimeracil/oteracil potassium (S-1) and particle beam therapy. After 7 months, CA19-9 was normal, and the patient has remained in partial remission with S-1 treatment. Ectopic pancreas tissues typically occur in the stomach and duodenum and rarely become cancerous. Here, we report the features of a rare and illustrative case of jejunal ectopic pancreatic cancer.