Follicular dendritic cell hyperplasia in plasma cell variant of Castleman's disease with interfollicular Hodgkin's disease.

We report a case of a multicentric plasma cell (PC) variant of Castleman's disease (CD) in association with interfollicular type of classic Hodgkin's disease (HD), both diseases identified in the same lymph node. The histologic features of CD were the classic ones, with hyperplastic and atrophic follicles, some with prominent mantle zones, hyalinzed vessels, and a very rich polyclonal proliferation of PCs in the interfollicular region. The presence of LCA-negative, but CD30- and CD15-positive typical and atypical Reed-Sternberg (RS) cells in the interfollicular region confirmed the presence of HD. In addition, many of the RS cells stained positive for EBV. CD35- and CD21-positive follicular dendritic cell (FDC) hyperplasia was a striking feature, a finding that has not been well documented in the PC variant of CD.