Cardiac amyloidosis: Pathology, nomenclature, and typing

Amyloidosis is an increasingly recognized cause of heart disease, caused by the deposition of misfolded protein within the heart. These proteins may deposit systemically and include the heart or deposit only within the heart muscle itself. In either case, cardiac symptoms may be the primary manifestation. The diagnosis is usually made by the pathologist identifying amyloid within a tissue sample. The diagnosis, however, does not end with such visual recognition of the presence of amyloid. Newer generation pharmacotherapeutic agents that are protein specific necessitate a closer evaluation to determine the type of protein being deposited and accurately conveying this to the treating clinician. Herein, the gross and histopathologic features of cardiac amyloidosis are reviewed along with a review of amyloid typing strategies (both direct and indirect) that may be employed in the diagnostic workup as well as the nomenclature standards for reporting.