1962 Rectal Amyloidosis: An Unusual Cause of Rectal Bleeding

Abstract

INTRODUCTION: Rectal amyloidosis is a rare cause of gastrointestinal bleeding and should be on the differential in patients with amyloid involvement of other organs. We present a case of rectal amyloidosis as the source of rectal bleeding. CASE DESCRIPTION/METHODS: A 76-year-old female with recently diagnosed multiple myeloma resulting in renal amyloidosis requiring hemodialysis, LV outflow obstruction from cardiac amyloidosis (on CyBORD regimen – cyclophosphamide, bortezomib, dexamethasone) presented with a 1-week history of hematochezia without associated abdominal pain, constipation, diarrhea, melena, nausea, or vomiting. Rectal examination revealed a large, firm anterior rectal mass. Laboratory findings were significant for profound anemia with Hgb 5.6 g/dL (compared to Hgb 7.2 g/dL one week prior). CT abdomen and pelvis showed a lumen-obliterating rectal mass measuring up to 9.3 cm and multiple perirectal calcific masses that were suspicious for metastases. She underwent flexible sigmoidoscopy and was noted to have a granular, non-obstructing, non-circumferential large mass in the rectum with active bleeding. Biopsies were consistent with amyloidosis. She was initiated on pelvic radiation therapy. A few weeks later, she passed away after cardiac arrest. Autopsy revealed cardiac and renal amyloidosis as well as rectal amyloidosis with pelvic lymph node involvement. There was no other gastrointestinal involvement of amyloid on autopsy. DISCUSSION: The overall prevalence of AL amyloidosis is between 6–10 cases per million person-years, correlating to approximately 2,200 annual cases in the US. In a retrospective review of 2,334 patients with amyloidosis, only 3% had biopsy proven amyloidosis of the gastrointestinal tract. Hepatic amyloid is the most common location of gastrointestinal amyloidosis and has been reported in up to 90% of patients with AL amyloid on autopsy. The clinical symptoms are based on the location of gastrointestinal amyloidosis and are usually nonspecific. This is a rare case of rectal amyloidosis without any other gastrointestinal amyloid involvement presenting with rectal bleeding. Gastrointestinal amyloidosis is treated with autologous stem-cell transplant or systemic chemotherapy. Our patient was treated with CyBORD chemotherapy and pelvic radiation for symptomatic rectal bleeding. Rectal amyloidosis should be included in the differential diagnosis of a rectal mass causing rectal bleeding in patients with history of AL amyloidosis.