Synchronous retroperitoneal Castleman's disease with clear cell renal cell carcinoma.

Castleman's disease is a rare non-clonal lymphoproliferative disorder and known to be associated with a number of disorders such as polyneuropathy, organomegaly, endocrinopathy, monoclonal protein and skin changes syndrome, Kaposi sarcoma, paraneoplastic pemphigus and plasma cell dyscrasias. The association of Castleman's disease with epithelial malignancy is not clear and limited to few case reports. We describe a case of synchronous Castleman's disease with renal cell carcinoma in a 53-year-old woman. She presented with right abdominal lump with feeling of heaviness. She also presented with vague discomfort in left hypochondrium for 15 years. The CT imaging of abdomen revealed two masses-one in right kidney and another in left anterior pararenal space of retroperitoneum. The patient underwent right radical nephrectomy with excision of left retroperitoneal mass. Histological examination revealed clear cell renal cell carcinoma and Castleman's disease, respectively. Role of interleukin-6 has been postulated as an important factor in association of Castleman's disease and epithelial malignancy.