Primary systemic amyloidosis presenting as polymyalgia rheumatica and giant cell arteritis

Primary systemic amyloidosis or AL-amyloidosis is an uncommon disease characterized by the accumulation in vital organs of a fibrillar protein consisting of monoclonal light chains. It is a plasma-cell dyscrasia related to multiple myeloma where clonal plasma cells in the bone marrow produce immunoglobulins that are amyloidogenic. A monoclonal component is present in the serum or urine of 90% of patients. The presentation of most patients with AL amyloidosis is usually related to congestive heart failure, nephrotic syndrome o peripheral neuropathy, but there are unusual features suggesting giant cell arteritis (GCA) and polymyalgia rheumatic (PMR). Although in the majority of AL cases the plasma cells clone is small, the assumption is that the outcome of the disease is uniformly fatal (median survival 12-15 months) and treatment is analogous to those used in malignant proliferative disease. We describe a patient with AL amyloidosis who presented with manifestations of GCA and PMR, and we review the main characteristics of primary amyloidosis.