Severe Pulmonary Hypertension Caused by Smoldering Plasma Cell Myeloma: An Autopsy Case of POEMS Syndrome

The POEMS syndrome (coined to refer to polyneuropathy, organomegaly, endocrinopathy, M protein, and skin changes) is a rare variant of plasma cell disorders with multiple systemic manifestations. Recently, pulmonary hypertension (PH) has become established as a complication, but pathological studies of this condition are scarce and the detailed pathogenesis remains to be elucidated. We present herein a case of a 49-year-old woman who was diagnosed as having idiopathic PH and was treated in accordance. However, she eventually died of respiratory failure and an autopsy revealed the presence of smoldering plasma cell myeloma and multiple organomegaly in addition to severe PH. The latter was attributed to stenosis and occlusion of the arterioles of the lungs due to marked plasma cell proliferation, quite different from the histology of idiopathic PH. From these findings, together with the clinical details, we concluded that the patient's PH was a complication of the POEMS syndrome. This case showed a unique pulmonary vascular pathology featuring plasma cell proliferation and it provides clues towards understanding the pathogenesis with this background.