title: Endoscopic and histopathological features of gastrointestinal amyloidosis.
abstract: Amyloidosis is a rare disorder, characterized by the extracellular deposition of an abnormal fibrillar protein, which disrupts tissue structure and function. Amyloidosis can be acquired or hereditary, and systemic or localized to a single organ, such as the gastrointestinal (GI) tract. Clinical manifestations may vary from asymptomatic to fatal forms. Primary amyloidosis (monoclonal immunoglobulin light chains, AL) is the most common form of amyloidosis. AL amyloidosis has been associated with plasma cell dyscrasias, such as, multiple myeloma. Secondary amyloidosis is caused by the deposition of fragments of the circulating acute-phase reactant, serum amyloid A protein (SAA). Common causes of AA amyloidosis are chronic inflammatory disorders. Although GI symptoms are usually nonspecific, histopathological patterns of amyloid deposition are associated with clinical and endoscopic features. Amyloid deposition in the muscularis mucosae, submucosa, and muscularis propria has been dominant in AL amyloidosis, leading to polypoid protrusions and thickening of the valvulae conniventes, whereas granular amyloid deposition mainly in the propria mucosae has been related to AA amyloidosis, resulting in the fine granular appearance, mucosal friability, and erosions. As a result, AL amyloidosis usually presents with constipation, mechanical obstruction, or chronic intestinal pseudo-obstruction while AA amyloidosis presents with diarrhea and malabsorption Amyloidotic GI symptoms are mostly refractory and have a negative impact on quality of life and survival. Diagnosing GI amyloidosis requires high suspicion of evaluating endoscopists. Because of the absence of specific treatments for reducing the abundance of the amyloidogenic precursor protein, we should be aware of certain associations between patterns of amyloid deposition and clinical and endoscopic features.
authors.affiliation: Akira Hokama, Kazuto Kishimoto, Tetsuo Hirata, Jiro Fujita, Department of Infectious, Respiratory, and Digestive Medicine, Faculty of Medicine, University of the Ryukyus, Okinawa 903-0125, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Hokama
authors.forename: Kazuto
authors.initials: K
authors.lastname: Kishimoto
authors.forename: Manabu
authors.initials: M
authors.lastname: Nakamoto
authors.forename: Chiharu
authors.initials: C
authors.lastname: Kobashigawa
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Hirata
authors.forename: Nagisa
authors.initials: N
authors.lastname: Kinjo
authors.forename: Fukunori
authors.initials: F
authors.lastname: Kinjo
authors.forename: Seiya
authors.initials: S
authors.lastname: Kato
authors.forename: Jiro
authors.initials: J
authors.lastname: Fujita