Modern concepts of primary systemic AL-amyloidosis: the viewpoint of a gastroenterologist

Abstract

The purpose of the review is to present an analysis of modern literature data on the pathogenesis, diagnosis and therapy of primary systemic amyloidosis of immunoglobulin light chains (AL-amyloidosis), to reveal the features of gastroenterological manifestations of the disease. AL-amyloidosis is caused by overproduction of immunoglobulin light chains by a clone of plasma cells located in the bone marrow, followed by the formation of amyloid.Deposition of amyloid in target organs (heart, kidneys, liver, gastrointestinal tract, peripheral and autonomic nervous systems, soft tissues) is accompanied by direct and indirect cytotoxic effects on organs and tissues. Gastrointestinal manifestations of AL-amyloidosis include liver damage, gastrointestinal bleeding, pseudo-obstruction of the small intestine and colon, the appearance of polyp-, diverticul-, tumor-like formations, malabsorption, impaired motility of the gastrointestinal tract, protein-losing gastropathy. Liver damage in patients with AL-amyloidosis, as a rule, is accompanied by minimal clinical manifestations, an increase of the level of alkaline phosphatase without any other reasons for this change. A detailed analysis of the Mayo Clinic’s practical guidelines for the diagnosis and treatment of AL-amyloidosis is presented. Diagnosis of gastrointestinal AL-amyloidosis is based on histomicroscopic analysis of biopsies of target organs with Congo red and subsequent examination in polarized light; mass spectrometry is the gold standard of diagnostic. Modern pharmacotherapy of AL-amyloidosis includes a combination of high-dose chemotherapy with monoclonal antibodies, proteasome inhibitors, cytostatics, hormones, as well as performing autologous stem cell transplantation. Correction of gastroenterological manifestations of the disease is based on the symptomatic therapy. Life expectancy of patients with AL-amyloidosis is determined by several prognostic models; the Boston University model, based on the definition of two markers, is most convenient for clinical use.