A rare synchrony of adenocarcinoma of the ampulla with an ileal gastrointestinal stromal tumor: A case report

BACKGROUND: This is a unique case of a patient who was found to have two extremely rare primary malignancies synchronously, i.e., an ampullary adenocarcinoma arising from a high-grade dysplastic tubulovillous adenoma of the ampulla of Vater (TVAoA) with a high-grade ileal gastrointestinal stromal tumor (GIST). Based on a literature review and to the best of our knowledge, this is the first report of this synchronicity. Primary ampullary tumors are extremely rare, with an incidence of four cases per million population, which is approximately 0.0004%. Distal duodenal polyps are uncommon and have a preponderance of occurring around the ampulla of Vater. An adenoma of the ampulla ( AoA) may occur sporadically or with a familial inheritance pattern, as in hereditary genetic polyposis syndrome such as familial adenomatous polyposis syndrome (FAPS). We report a case of a 77-year-old male who was admitted for painless obstructive jaundice with a 40-pound weight loss over a two-month period and who was subsequently diagnosed with two extremely rare primary malignancies, i.e., an adenocarcinoma of the ampulla arising from a high-grade TVAoA and a high-grade ileal GIST found synchronously. CASE SUMMARY: A 77-year-old male was admitted for generalized weakness with an associated weight loss of 40 pounds in the previous two months and was noted to have painless obstructive jaundice. The physical examination was benign except for bilateral scleral and palmar icterus. Lab results were significant for an obstructive pattern on liver enzymes. Serum lipase and carbohydrate antigen-19-9 levels were elevated. Computed tomography (CT) of the abdomen and pelvis and magnetic resonance cholangiopancreatography were consistent with a polypoid mass at the level of the common bile duct (CBD) and the ampulla of Vater with CBD dilatation. The same lesions were visualized with endoscopic retrograde cholangiopancreatography. Histopathology of endoscopic forceps biopsy showed TVAoA. Histopathology of the surgical specimen of the resected ampulla showed an adenocarcinoma arising from the TVAoA. Abdominal and pelvic CT also showed a coexisting heterogeneously enhancing, lobulated mass in the posterior pelvis originating from the ileum. The patient underwent ampullectomy and resection of the mass and ileo-ileal side-to-side anastomosis followed by chemoradiation. Histopathology of the resected mass confirmed it as a high-grade, spindle cell GIST. The patient is currently on imatinib, and a recent follow-up positron emission tomography (PET) scan showed a complete metabolic response. CONCLUSION: This case is distinctive because the patient was diagnosed with two synchronous and extremely rare high-grade primary malignancies, i.e., an ampullary adenocarcinoma arising from a high-grade dysplastic TVAoA with a high-grade ileal GIST. An AoA can occur sporadically and in a familial inheritance pattern in the setting of FAPS. We emphasize screening and surveillance colonoscopy when one encounters an AoA in upper endoscopy to check for FAPS. An AoA is a premalignant lesion, particularly in the setting of FAPS that carries a high risk of metamorphism to an ampullary adenocarcinoma. Final diagnosis should be based on a histopathologic study of the surgically resected ampullary specimen and not on endoscopic forceps biopsy. The diagnosis of AoA is usually incidental on upper endoscopy. However, patients can present with constitutional symptoms such as significant weight loss and obstructive symptoms such as painless jaundice, both of which occurred in our patient. Patient underwent ampullectomy with clear margins and ileal GIST resection. Patient is currently on imatinib adjuvant therapy and showed complete metabolic response on follow up PET scan.