Pulmonary arterial hypertension due to pulmonary vascular amyloid deposition in a patient with multiple myeloma

Systemic amyloidosis is characterized by amyloid deposition throughout the body and subsequent dysfunction of various organs. Although pulmonary amyloidosis does occur, pulmonary hypertension (PH) caused by amyloidosis is extremely rare. In most of these cases, amyloid deposition occurred diffusely in alveolar septa, indicating that PH was due to lung disease and/or hypoxia. On the other hand, the mechanism of PH due to amyloid deposition in the pulmonary arteries has never been demonstrated. Here, we report the first case of PH due to amyloid deposition in pulmonary elastic arteries and muscular artery, which was complicated by multiple myeloma (MM). In the autopsy specimen of the patient, amyloid deposition was found mainly in the pulmonary arterial media, along with intimal thickening with luminal narrowing. PH thus appeared to be caused by marked decrease of pulmonary elasticity due to the amyloid deposition in the arterial media that resulted in stasis of the blood flow and subsequent luminal narrowing. Our present data demonstrates a new concept of PH caused by amyloidosis, namely, pulmonary arterial hypertension due to amyloidosis.