Primary Amyloidosis and Hematochezia: An Unexpected Discovery

Abstract

Introduction: Primary amyloidosis is a rare entity with only 1200 to 3200 new cases reported each year. Clinically apparent gastrointestinal (GI) involvement with the disease is seen even less frequently; quoted as low as 1% in some reviews. The disease is due to extra-cellular deposition of fibril-forming monoclonal immunoglobulin light-chains that can affect any organ system, including the GI tract, presenting as GI bleeding, diarrhea, or other symptomatology. We present here a rare case of primary amyloidosis presenting with an isolated episode of hematochezia and chronic diarrhea. Case Report: A 59 year-old female with history of thyroid cancer and primary (AL) amyloidosis on renal biopsy for hypoalbunemia as well as a bone marrow biopsy consistent with plasma cell myeloma presented with an episode of hematochezia. For one-month prior, she had chronic diarrhea with ten to twelve episodes of loose, liquid, non-bloody stools daily that are only minimally improved with loperamide. These symptoms had not changed until one day prior to presentation, when she experienced a single episode of hemaotchezia when wiping prompting her to seek medical care. Physical exam was unremarkable. Her infectious diarrheal stool work-up was negative as well as a normal red blood cell count. A CAT scan of the abdomen demonstrated wall edema and thickening of the descending colon, sigmoid colon and rectum. Based on these findings, a colonoscopy was performed for further evaluation during which, there were multiple areas of protuberant, sub mucosal hematomas mixed with small mucosal hemorrhages scattered throughout the colon concerning for visible vessels versus vascular infiltration of amyloid. Multiple biopsies of these affected areas demonstrated changes consistent with ulcer formation and a Congo red stain showing apple green birefringence in walls of several small vessels consistent with amyloid deposition in these vessels and thus amyloid involvement of the colon. Discussion: Gastrointestinal manifestations are uncommon in primary amyloidosis with biopsy diagnosed disease and clinically apparent disease occurring in only 8% and 1% respectively in one retrospective review. However, gastrointestinal bleeding or diarrhea can occur as a presenting symptom in patients with amyloidosis. This may be caused by ischemia, infarction, and ulceration or from generalized oozing without an observed source. The clinical suspicion for amyloid involvement of the colon in a patient presenting with diarrhea and scant hematochezia is usually low even with a previous diagnosis of renal amyloid involvement given the rarity of such findings, however, we present here a case of this unexpected discovery.