Sigmoid Colon Polyp as Initial Presentation of Metastatic Papillary Renal Cell Carcinoma

Abstract

Introduction: Renal cell carcinoma (RCC) accounts for 3% of all adult malignancies, with 25-30% of patients having metastatic disease upon initial presentation. Metastasis is most common to the lungs, bone, liver, brain, lymph nodes, while metastasis to the gastrointestinal tract is rare, with the large bowel being the least common site. A 75-year-old white male with a past medical history of leukemia, renal insufficiency, and internal hemorrhoids presented with abdominal pain, nausea, vomiting, diarrhea, testicular pain, and decreased appetite. Esophagogastroduodenoscopy (EGD) was performed that revealed mild gastritis, a hiatal hernia, and no active bleeding. Colonoscopy revealed diverticulosis and non-bleeding internal hemorrhoids. A semi-pedunculated 0.2-cm distal sigmoid colon polyp was removed and the histology was compatible with RCC. The immunohistochemical (IHC) analysis was positive for CAM 5.2 and AE1/AE3 (suggesting renal cell origin) and PAX-2 and PAX-8 (suggesting RCC). IHC staining also revealed positive inhibin (suggesting no adrenal cortical carcinoma origin) combined with negative primary colon malignancy markers CDX-2, CK20, and CEA and negative neuroendocrine markers synaptotrophysin, chromogranin, and CD56. Negative chromophobe RCC markers CD117 and CK7 combined with a positive vimentin and histological H&E staining suggest sigmoid colon polyp cells of papillary RCC origin. A computed tomography (CT) of abdomen with contrast showed 3 masses in right kidney, with maximum diameter of 4 cm, and a single mass in the left kidney, with a maximum diameter of 2 cm. There was no history of a nephrectomy and no other lesions were detected. These results, together with histological analysis and evidence of renal masses on CT, provide a reasonable assumption that the sole sigmoid colon polyp favors metastasis from a primary papillary RCC. To be the best of our knowledge, this is the first reported case of metastatic papillary RCC that metastasized to the colon and presented as a single polyp. RCC metastasis to the gastrointestinal tract is quite rare, with metastasis to the stomach and small bowel significantly more common than the colon. The sporadic colon metastasis case reports that do exist describe metastasis to multiple colon sites and/or colon polyps, with the majority involving clear cell RCC metastasis and not papillary RCC metastasis. Involvement of atypical RCC metastasis sites, such as the colon, usually occur in cases that have recurrence many years after kidney resection, which our patient never had. Our patient had vague abdominal symptoms likely due to gastritis and acute orchitis that led to subsequent work-up and eventual diagnosis of newonset papillary RCC and metastasis.