Idiopathic multicentric Castleman's disease. A clinicopathologic and immunohistochemical study of five cases

Histologically, three lesions exhibited a mixed type of Castleman's disease, and two exhibited the hyaline-vascular type. The majority of the germinal centers were of the hyaline-vascular or epithelioid germinal type, with a few hyperplastic germinal centers. The interfollicular area was characterized by prominent vascularity. Moderate to large sheets of plasma cells were observed in three mixed type cases. The polytypic nature of B-lymphocytes was demonstrated by immunohistochemistry and polymerase chain reaction. Immunohistochemical study demonstrated that the majority of germinal centers exhibited a tight/concentric pattern of FDC network. Few CD57-positive T-cells were observed in the hyaline-vascular and epithelioid follicles. The lack of CD57-positive T-cells appears to be related to the formation of abnormal germinal centers in the MCD.