AL Amyloidosis is a plasma cell disorder characterized by the aggregation and deposition of insoluble amyloid fibrils derived from misfolding of monoclonal immunoglobulin light chains usually produced by a plasma cell tumor. It usually presents as primary systemic amyloidosis (PSA) with multiple organ involvement and less frequently as primary localized amyloidosis (PLA) restricted to a single organ. The disease is AL amyloidosis (MONDO_0019438). Also known as: Light-chain amyloidosis, primary amyloidosis.