Case report: A case of laterally spreading duodenal cancer with slight submucosal invasion accompanied with concurrent lymph nodes metastasis

A 70‐year‐old female diagnosed with duodenal cancer was referred to our hospital. Esophagogastroduodenoscopy revealed an 80 mm flat elevated lesion was located in the inner wall of the second part of the duodenum and the lesion completely involved major papilla. Endoscopic submucosal dissection (ESD) was performed and the lesion was resected in a single piece including the part of the major papilla. The pathological examination of the resected specimen showed moderately differentiated adenocarcinoma limited in the mucosa in most parts of the lesion, however, cancer cells invaded into the submucosal layer with an invasion depth of 100 μm in only a small area. Lymph ductal involvement was confirmed in that area. Two months after ESD, pylorus‐preserving pancreatoduodenectomy combined with extended lymph node dissection was additionally performed. The postoperative pathological examination revealed lymph ductal involvement was observed in the regional lymph node. While the postoperative clinical course was uneventful, systematic metastasis was pointed out 5 months after surgery. The patient was died 9 months after surgery. Due to its rarity, the natural history of duodenal cancer has been still unclear. In this case, even a lesion with only a localized small area of submucosal invasion developed systemic metastasis, indicating the high malignant potential of duodenal cancer.