The clinicopathological comparison among nodal cases of idiopathic multicentric Castleman disease with and without TAFRO syndrome.

Multicentric Castleman disease (MCD) is a systemic inflammatory disease potentially caused by an increase in the serum interleukin-6 (IL-6) level. Idiopathic MCD (iMCD) is histopathologically classified into three types: plasmacytic (PC), mixed, and hypervascular (hyperV) types. Recently, a unique clinical phenotype with a poor prognosis overlap with iMCD, thrombocytopenia, anasarca, fever, renal failure or reticulin fibrosis, and organomegaly (TAFRO syndrome), has been reported from Japan, but its detailed clinicopathological features remain unclear. In this study, we performed a clinicopathological analysis of 70 nodal cases of iMCD with and without TAFRO syndrome (n = 37 versus n = 33). Compared with iMCD without TAFRO, iMCD with TAFRO showed more atrophic lymphoid follicles (LF), greater distances between follicles, increased glomeruloid vascular proliferation within the germinal center, and increased follicular dendritic cells. In addition, the hyperV type in particular demonstrated severe atrophic LF and interfollicular vascular proliferation. Among the mixed-type cases, the serum IL-6 levels in iMCD with TAFRO were significantly higher than those in iMCD without TAFRO. Furthermore, compared to iMCD without TAFRO, the numbers of immunoglobulin G4 (IgG4)-positive and CD38-positive plasma cells were significantly decreased in iMCD with TAFRO.