Aims: Castleman's disease (CD) is a rare heterogeneous disorder that is associated with an increased risk of developing lymphoma. Whether CD is primarily hyperplastic or neoplastic in origin is not yet clear. The aim of this study was to investigate CD further by determining the clonality status of its lymphocyte populations.
Methods and results: We reviewed 20 patients with CD, 15 with the hyaline-vascular type and five with the plasma cell type. Immunoglobulin (JH) and T-cell receptor (TCR) gene rearrangements were examined using polymerase chain reaction and Southern blotting techniques. B-lymphocyte clonality was also assessed by flow cytometry (FC) and by immunohistochemistry (IHC). The age range of the patients was 15-66 years: nine female and 11 male. Monoclonal rearrangement of the immunoglobulin (JH) gene was detected in only one case. No cases were positive for monoclonal rearrangement of the TCR gene. All of the cases except one were negative for immunoglobulin light chain restriction by both FC and IHC.
Conclusions: The lymphoid cells in CD are most commonly polyclonal in origin, which supports a non-neoplastic origin. However, rare cases may show lymphocyte monoclonality, which could represent the development of a neoplastic population. The latter cases should be followed closely.