Renal cell carcinoma has a strong tendency to metastasize many years after surgical resection, and it has the potential to spread to almost all sites, including the lungs, lymph nodes, liver, bones, adrenal glands, kidneys, brain, heart, spleen, intestine and skin [15]. However, only 4% of RCCs metastasize to the small intestine, and duodenal metastasis occurs less frequently than metastasis to the jejunum and ileum[16]. Of note, approximately one-half of patients who have undergone nephrectomy for RCC develop widespread metastases despite the primary RCC being localized[2].
The duodenal metastasis can be involved by direct invasion of the tumor, or through lymphatic, transcoelomic or hematogenous spread and also direct invasion of pancreatic metastasis[3]. According to the previous reports, duodenal involvement of RCC can be presented with jaundice, anemia and gastrointestinal bleeding, malabsorption and obstruction[4]. In our case, the patient presented with anemia and hypoproteinemia, which indicates chronic gastrointestinal bleeding and malnutrition. Most of the metastatic RCCs in the duodenum were primarily in the second portion with or without pancreatic involvement[5–6], as in our case, the metastatic RCC was located in the second portion without pancreatic involvement.
The endoscopic manifestations of duodenal metastasis are quite miscellaneous. It has been reported to be submucosal mass lesion with glistening mucosa[5], duodenal ulcer[9], ulcerated polypoid mass[10–11], fungating mass[12], ampullary mass[13], multiple nodules of varying sizes or raised plaques[14], etc. In our case, the mass is huge, irregular and semitransparent, this particular feature of the metastatic duodenal mass has never been reported previously.
The treatment of choice for localized metastatic RCC is surgery. In previous reports, most of the patients with duodenal metastasis of RCC were treated with Whipple’s operation; however, there were successful surgeries of duodenal saving segmental or wedge resection[7–8]. Our patient underwent Whipple’s operation with excellent recovery. No adverse and unanticipated events happened.
Our case is very unique due to its rarity and particular endoscopic features. Besides, our patient’s clinical data is very complete, including MRI appearances, endoscopic manifestations, gross specimen of pancreatoduodenectomy, histopathology and immunohistopathology of postoperative specimen.