Hyaline vascular type of unicentric Castleman's disease with proliferation of glomerular endothelial cells

Castleman’s disease (CD) is a lymphoproliferative disorder of uncertain etiology. It can be classified histopathologically as hyaline vascular (HV) or plasma cell (PC) type; and clinically as unicentric or multicentric. Multicentric CD mostly manifests as the PC type and is often associated with a variety of systemic complications, although renal complications are uncommon. We present here a case of HV type, unicentric CD with a variety of systemic and renal complications, including the proliferation of glomerular endothelial cells. Various cytokines are thought to be involved in the etiology of this disease, especially interleukin-6 (IL-6) and vascular endothelial growth factor (VEGF), which are the main cytokines inducing systemic complications. It has been reported that most PC types and/or multicentric types of CD show increasing levels of serum IL-6 and VEGF, as well as systemic symptoms. Although the current case showed high serum IL-6 and VEGF levels as well as systemic symptoms, the pathological and clinical type were of the HV type and unicentric type, respectively. After immunosuppressive therapy, the serum levels of IL-6 and VEGF returned to the normal range, and systemic complications, including renal involvement, also improved. We report the possibility of pathogenesis via the serum and the pathology of this rare case.