Endoscopic hydrostatic balloon dilation of ulcer-induced pyloric stenosis in rheumatoid arthritis and secondary amyloidosis

Amyloidosis of the gastrointestinal tract and the liver: clinical context, diagnosis and management

Amyloidosis is a group of disorders that can manifest in virtually any organ system in the body and is thought to be secondary to misfolding of extracellular proteins with subsequent deposition in tissues. The precursor protein that is produced in excess defines the specific amyloid type. This requires histopathological confirmation using Congo red dye with its characteristic demonstration of green birefringence under cross-polarized light. Gastrointestinal (GI) manifestations are common and the degree of organ involvement dictates the symptoms that a patient will experience. The small intestine usually has the most amyloid deposition within the GI tract. Patients generally have nonspecific findings such as abdominal pain, nausea, diarrhea, and dysphagia that can often delay the proper diagnosis. Liver involvement is seen in a majority of patients, although symptoms typically are not appreciated unless there is significant hepatic amyloid deposition. Pancreatic involvement is usually from local amyloid deposition that can lead to type 2 diabetes mellitus. In addition, patients may undergo either endoscopic or radiological evaluation; however, these findings are usually nonspecific. Management of GI amyloidosis primarily aims to treat the underlying amyloid type with supportive measures to alleviate specific GI symptoms. Liver transplant is found to have positive outcomes, especially in patients with specific variants of hereditary amyloidosis.

Amyloid and the GI tract

Amyloidosis is characterized by the extracellular deposition of an abnormal fibrillar protein, which disrupts tissue structure and function. Amyloid may be localized to a single organ, such as the GI tract, or be systemic where the amyloid type is defined by the respective fibril precursor protein. Among patients with systemic amyloidosis, histological involvement of the gastrointestinal (GI) tract is very common but often subclinical. The presence and pattern of GI symptoms varies substantially, not only between the different amyloid types but also within them. GI presentations are frequently nonspecific and include macroglossia, dyspepsia, hemorrhage, a change in bowel habit and malabsorption. Endoscopic and radiological features of amyloidosis are also nonspecific, with the small intestine most commonly affected. In the absence of specific treatments for GI amyloidosis, therapy is aimed at reducing or eliminating the supply of the respective fibril precursor protein. Supportive measures such as nutritional support and antidiarrheal agents should be instigated while awaiting the clinical improvement associated with a successful reduction in the abundance of the fibril precursor protein. GI tract surgery should be performed only if the benefits clearly outweigh the risks, as there is a risk of decompensation of organs affected by amyloid.

Systemic amyloidosis and the gastrointestinal tract

Systemic amyloidosis is characterized by the extracellular deposition of protein in an abnormal fibrillar form. Several different types of amyloidosis exist, each defined by the identity of their respective fibril precursor protein. Among patients with systemic amyloidosis, histological involvement of the gastrointestinal tract is very common but is often subclinical. Conversely, primary diseases of the gastrointestinal tract can cause systemic amyloidosis; for example, AA amyloidosis can occur secondary to IBD. The presence and pattern of gastrointestinal symptoms varies substantially, not only between the different types of amyloidosis but also within them. Typical clinical presentations, most of which are nonspecific, include macroglossia, hemorrhage, motility disorders, disturbance of bowel habit and malabsorption. Endoscopic and radiological features are also nonspecific, with the small intestine most commonly affected. Currently, the aim of therapy for amyloidosis is to slow amyloid formation by reducing the abundance of the fibril precursor protein. No specific treatments for the gastrointestinal symptoms of systemic amyloidosis are available; however, case reports and small published series encourage nutritional support for patients with motility disorders and pharmacological agents for treatment of diarrhea. Surgical procedures should be contemplated only in an emergency setting because of the risk of decompensation of organs affected by amyloid deposition.