S2055 Systemic Immunoglobulin Light Chain (AL) Amyloidosis Involving Large Intestine

INTRODUCTION: Amyloidosis is characterized by extracellular tissue deposition of fibrils resulting in disruption of tissue structure and function. Gastrointestinal (GI) amyloidosis commonly results from chronic inflammatory disorders (AA amyloidosis) and is less commonly seen in AL amyloidosis. Here we report a rare case of biopsy-proven symptomatic AL amyloidosis involving the large intestine. CASE DESCRIPTION/METHODS: A 50-year-old male with a history of end-stage renal disease secondary to AL amyloidosis presented to the ER with complaints of abdominal pain, diarrhea, weight loss, and bright red blood per rectum. On arrival, his temperature was 98.4°F; BP and HR were 114/68 mm/hg and 111 beats/min, respectively. Physical examination was significant for diffuse abdominal tenderness with voluntary guarding. Laboratory findings were significant for WBC 13 K/ul, Hb 5.8 g/dl, BUN 34 mg/dl, creatinine 9.84 mg/dl, and albumin 1.9 g/dl. C- reactive protein (4.9 mg/dl) and fecal calprotectin (2809 ug/g) were elevated. The patient was resuscitated with two units of pRBCs. Infectious workup, including the stool studies, were negative. Abdominal CT showed a long segment of colonic mural thickening involving the ascending and transverse portions with submucosal edema, pericolonic fat stranding, and vascular congestion and the findings were consistent with colitis. Patient underwent lower GI endoscopy, which showed a large amount of adherent blood clots covering the descending colon. Flexible sigmoidoscopy a few days later revealed patchy areas of erythema with ulceration from the sigmoid colon to transverse colon, with a stricture in the transverse colon, which was consistent with chronic ischemia. Histological examination of the colon biopsy revealed ulceration and inflammation. Congo Red and Thioflavin T stains were performed on the colon biopsy, which was positive for amyloid. DISCUSSION: Colon biopsy confirmed GI involvement of amyloidosis. The patient is planned for colon resection since amyloid protein accumulation in the organs is generally an irreversible phenomenon. After the surgical resection, he is planned for chemotherapy.Patient presenting with gastrointestinal symptoms in the setting of primary amyloidosis should be evaluated for GI involvement. It is crucial to attempt early detection as accumulation is reversible at an early stage. Early detection and treatment of this condition would improve the overall prognosis.Figure 1.: CT Abdomen: Axial view demonstrating colonic mural thickening with pericolonic fat stranding.Figure 2Figure 3