1634 Extracolonic Neoplasm From Colonic Polyps: A Case of Metastatic Prostate Cancer Diagnosed From a Colonic Polyp

Abstract

INTRODUCTION: Prostate Cancer is the 2nd most common cancer among men in the US. Prostate Cancer frequently metastasizes to the bones, lymph nodes, lungs, liver, and brain. Very rarely, patients can develop metastases to the GI tract. We are presenting a patient that was diagnosed with metastatic prostate cancer after a colon biopsy. CASE DESCRIPTION/METHODS: A 61-year-old gentleman with no significant past medical history, presented with constipation, weak urinary stream, in addition to remote fall followed by lower back pain, trouble ambulating, and an unintentional 40 lb weight loss. He did not have any history of melena, hematochezia, abdominal pain or family history of cancers Examination was only evident of tenderness overlying lumbar vertebrae. He underwent CT Abdomen/Pelvis which showed sclerotic vertebral bone lesions in addition to abnormal thickening of the mid to lower rectal wall with adjacent perirectal soft tissue masses suspicious for rectal cancer with adjacent conglomerate lymphadenopathy/tumor. Colonoscopy revealed diminutive sigmoid sessile polyps which was removed by cold snare and cold biopsy in addition to an area of ulceration in the proximal rectum. Surprisingly the pathology of the polyps and rectal ulceration was consistent with metastatic prostate adenocarcinoma. He is planned to be started on chemotherapy with Docetaxel. DISCUSSION: Prostate cancer may invade the rectum however it remains rare to have metastatic colonic polyps from a prostate cancer. It has been reported to discover metastatic colonic polyps from breast, lung, skin (melanoma) cancer, however the finding of metastatic colonic polyps from a prostate cancer is rare and portends a sinister prognosis. In the light of this infrequent finding it becomes imperative to consider an extracolonic cause as the source of a colonic polyp especially in patients with known or in suspicion for a primary cancer. The mechanism of metastasis to the colonic is thought to be by hematogenous or lymphatic spread, however, rectal involvement often occurs by local tissue invasion. The clinical scenario in our patient is peculiar since there were no prior diagnoses of primary cancer. An extracolonic metastatic polyp may sometimes be the earliest sign of recurrent prostate cancer.