Reporting the Rarest of Rare! Duodenal Adenocarcinoma in a Patient with Prior Rectal Adenocarcinoma

Abstract

Multiple GI malignancies in the same patient have been reported in literature. However, metachronous duodenal adenocarcinoma in a patient with prior rectal adenocarcinoma has been very rarely described. 50 year old black male with PMH of SCC head and neck status post radiation therapy underwent a colonoscopy for positive FOBT. Findings included an ascending colon polyp (tubular adenoma with focal surface high grade dysplasia - unclear margins), a splenic flexure polyp (tubular adenoma with focal surface high grade dysplasia, extending within 1 mm of the cauterized margin) and a rectal polyp (consistent with invasive, moderately differentiated adenocarcinoma extending into the submucosa). PET scan was negative for nodal or distant metastasis. EUS revealed stageT2 N0 disease. Patient was referred for surgery to a different hospital. Repeat colonoscopy showed residual ascending colon polyp (benign pathology). Biopsies from prior rectal polypectomy site were benign. EUS did not reveal any rectal lesion or lymphadenopathy. In light of discordant EUS findings, the patient and surgeon opted for transanal minimally invasive laparoscopic resection of rectal lesion for diagnostic and therapeutic purposes. Pathology revealed focal adenomatous change with negative margins. A month later the patient was re-admitted with nausea, vomiting, abdominal pain and poor oral intake. CT abdomen was normal. EGD was unremarkable till the second portion of duodenum. A small bowel follow through showed markedly dilated stomach and duodenum with a transition point at the ligament of Treitz. Push enteroscopy revealed an obstructing polypoid mass in third portion of duodenum. Biopsies were consistent with invasive adenocarcinoma. Whipple's procedure was performed. Two months later, he returned with similar symptoms. CT abdomen revealed innumerable metastases to liver, lymphadenopathy, and phlegmonous inflammatory changes within abdomen. Patient elected home hospice. Because of their rarity, indifferent symptomatology, and diagnostic elusiveness, small bowel tumors are often missed or diagnosed and treated late in their course with correspondingly poor results. The diagnostic difficulty is compounded when these tumors arise metachronously in patients with treated colorectal cancers. High index of suspicion coupled with effective communication between gastroenterologists, radiologists, surgeons and pathologists is essential in appropriate management of these patients.