Increase in soluble CD138 in bronchoalveolar lavage fluid of multicentric Castleman's disease

Multicentric Castleman's disease (MCD) is a rare and often incurable lymphoproliferative disorder. It is typically a systemic illness, but occasionally manifests primarily as a pulmonary parenchymal disease with massive infiltration of CD138 (syndecan-1)-positive plasma cells. This is the first report to demonstrate a marked elevation of soluble CD138, despite the absence of plasma cells, in BAL fluid in an MCD patient with pulmonary involvement. This finding suggests that the quantitative measurement of soluble CD138 in BAL fluid may reflect plasma cell infiltration and disease activity in the lungs of patients with MCD.