S1779 Gastrointestinal Amyloidosis: An Unexpected Cause of Diarrhea in an HIV Patient

Abstract

Introduction: Systemic amyloidosis is a rare multisystem disease caused by the deposition of misfolded protein in various organs, including the gastrointestinal (GI) tract. Amyloidosis occurs in the setting of chronic inflammatory states. The association of acquired immune deficiency syndrome (AIDS) and amyloidosis has been rarely described. We present a case of amyloidosis involving the colon in a patient with uncontrolled human immunodeficiency virus (HIV). Case Description/Methods: A 50-year-old male presented with non-bloody diarrhea of 2 weeks duration. He had a past medical history of Hepatitis C, active IV heroin use, and AIDS. Most recent CD4 count was less than 10 cells/mm3 with an HIV viral load of 36,000 copies/mL. Laboratory workup on admission was significant for severe normocytic anemia, leukopenia, and acute renal failure with proteinuria. An extensive infectious evaluation of the patient’s persistent diarrhea was unremarkable. Computed tomography (CT) scan of the abdomen demonstrated diffuse wall thickening of the sigmoid and descending colon suggestive of colitis. Flexible sigmoidoscopy was performed to further characterize the etiology of colitis. Pale, friable mucosa with scattered telangiectasia was noted on gross examination. Colonic tissue biopsy revealed the presence of extensive perivascular and lamina propria amyloid deposition, which was confirmed by Congo red staining. Apple green birefringence was observed on polarizing microscopy exam. Negative HSV, CMV, AFB, and HHV stains were noted on pathological exam. Subsequent tissue typing was consistent with AA Amyloid secondary to chronic inflammatory state. Discussion: The two most common type of amyloidosis are Amyloid Light chain (AL) amyloidosis and serum Amyloid A (AA) amyloidosis. AL amyloid occurs in the presence of a plasma cell dyscrasia and AA amyloidosis due to ongoing or recurring inflammation from chronic disease. GI involvement has been described in all major systemic amyloid subtypes. The most common GI presentations include GI bleeding, weight loss, diarrhea, and dysmotility. Patients with uncontrolled HIV are at risk for recurrent infections and therefore chronic inflammation. This case highlights the possibility of gastrointestinal AA amyloidosis as an underlying etiology of persistent diarrhea in a patient with AIDS. While amyloidosis secondary to AIDS is rare, it should be considered as part of the broad differential diagnosis of diarrhea in this patient population.Figure 2.: Tissue biopsy showing extensive perivascular and lamina propria amyloid deposition confirmed by Congo red staining.