Systemic Amyloid Light Chain Amyloidosis With Repeated Syncope Due to Severe Orthostatic Hypotension Caused by Autonomic Neuropathy: A Case Report.

Amyloid light chain (AL) amyloidosis is a disease in which ALs, which are proteins with fibrous structures, are deposited in systemic organs, causing functional impairment. Diagnosis is often difficult because of non-specific and varied symptoms. We report a case of systemic AL amyloidosis that was diagnosed as a result of repeated syncope. A 76-year-old woman was brought to the emergency room with multiple episodes of loss of consciousness over the past five years. She visited the major hospital, where pulmonary thromboembolism and symptomatic epilepsy were considered possible causes. Orthostatic hypotension was observed after being transferred to our hospital for rehabilitation. We performed diagnostic tests, including blood tests, imaging, and a head-up tilt test, which confirmed severe orthostatic hypotension. A gastrointestinal biopsy with Congo red staining confirmed the presence of amyloid deposits. AL amyloidosis (λ) was diagnosed using immunohistochemical staining. Given her age and prolonged bed rest, she was determined that she could not tolerate chemotherapy and was discharged upon her request. To the best of our knowledge, this is the first report of systemic AL amyloidosis presenting with orthostatic hypotension severe enough to cause syncope due to autonomic neuropathy. Autonomic neuropathy should be considered, and amyloidosis should be included in the differential diagnosis when a patient presents with recurrent syncope.