Molecular analysis of clonality in Castleman's disease.

Castleman's disease (CD) is a rare atypical lymphoproliferative disorder that is morphologically and clinically heterogenous and is associated with a risk of developing malignant lymphoma. We report the clonality status of CD tissues in 34 patients, including 14 patients infected by the human immunodeficiency virus (HIV). Four patients presented a localized form and 30 presented a multicentric form. Two cases were associated with B-cell lymphoma, 3 cases with Hodgkin's disease, and 9 cases (8 HIV+) with Kaposi's sarcoma. Histologically, 8 cases were of the hyaline-vascular type and 26 were of the plasma cell or mixed types. The Ig and T-cell receptor (TCR) V(D)J rearrangements were analyzed using polymerase chain reaction and Southern blot. Clonal IgH rearrangements were detected in only 4 cases, ie, 2 associated with B-cell lymphoma, 1 with Hodgkin's disease, and 1 case without malignancy. A TCR gamma rearrangement of restricted junctional size was amplified in 1 HIV+ case. Finally, polyclonal VH-JH and V gamma-J gamma rearrangements were detected in the large majority of the cases, irrespective of pathologic subtypes, clinical forms, and HIV status. The lymphoid component in CD is therefore commonly reactive, and the rare occurrence of detectable monoclonal lymphoid contingents may be caused by secondary molecular events.