A chromosomal abnormality in hyaline vascular Castleman's disease - Evidence for clonal proliferation of dysplastic stromal cells

The pathogenesis of the hyaline vascular variant of Castleman's disease is currently unknown; however, vascular and dendritic cell proliferations are common in this disorder. We report a clonal karyotypic abnormality (46,XX,t (1;16) (p11;p11), del(7)(q21q22),del(8)(q12q22)) in 15 of 20 cells obtained after short-term stromal cultures of a typical case of hyaline vascular Ca stleman's disease (HVCD). There was no histologic, immunohistochemical, or genotypic evidence of a clonal lymphoid or plasma cell proliferation suppor ting origin of this aberration from the stromal component, possibly dendrit ic cells. We re-examined 15 previous cases of HVCD and identified a spectru m of dysplastic changes in the follicular dendritic cells (FDC) of atrophic lymphoid follicles, with some cases showing expansions of FDC networks by CD21 immunostaining. We propose that localized clonal proliferations of str omal elements, particularly follicular dendritic cells, occur in typical HV CD and likely explain the increased incidence of FDC sarcomas in these pati ents.