Supplementary Material for: AL-amyloidosis as a rare cause of upper gastrointestinal bleeding: A case report and systematic literature review

Introduction
Amyloidosis is a rare disease characterized by the deposition of misfolded proteins in different organs leading to tissue damage and organ failure. The immunoglobulin light chain produced by a monoclonal B-cell is one of more than 30 proteins identified to cause amyloidosis. Most commonly affecting the heart and kidneys, AL (amyloid, light chain) -amyloidosis can occur in any organ except for the central nervous system and carries a high morbidity and mortality. Gastrointestinal involvement is observed rather rarely and can present with intestinal obstruction, weight loss, hematochezia, malabsorption or hematemesis. In this case report and systematic review, we present a 76-year-old male patient with new onset recurrent hematemesis and melena due to duodenal AL-amyloidosis and give a summary on the reported cases of upper gastrointestinal bleeding caused by the disease.

Case report
The report of this case was guided by the CARE guidelines and served as an example to allow for a discussion of the specific aspects of upper gastrointestinal bleeding in AL amyloidosis. A comprehensive literature search was conducted using the databases PubMed, EMBASE and GoogleScholar. After applying the eligibility criteria, a total count of 26 were included into the systematic review which was reported according to the PRISMA checklist.
The reported case showed recurrent hematemesis as the initial symptom of AL-amyloidosis due to B cell dyscrasia and appeared to be characteristic of patients presenting with primary gastrointestinal involvement. Summarizing the biometric and clinical details of the individuals included into the systematic review, we observed a mean age of 66 years, a slight female predominance and a preferred clinical manifestation in the stomach and duodenum with localized disease in 38% of all cases.

Conclusion
Although being a rare cause of upper gastrointestinal bleeding, AL-amyloidosis should be considered in patients with endoscopic findings of systemic disease and a clinical condition of suspected or known B cell dyscrasia. An early diagnosis is crucial for patients with AL amyloidosis as the disease often shows a rapid progression and treatment with combined immuno-chemotherapy is well tolerated and highly efficient.