Renal cell carcinoma and systemic amyloidosis: demonstration of AA protein and review of the literature.

A case of renal cell carcinoma associated with systemic amyloidosis in a patient with nephrotic syndrome is presented. Amyloid deposits were present in the resected tumor, ipsilateral kidney, and spleen. Potassium permanganate treatment of histologic sections as well as immunoperoxidase staining identified AA protein within the amyloid. Surgical removal of the tumor caused marked remission of the patient's proteinuria. Thirty-nine previously reported cases of renal cell carcinoma with amyloidosis are reviewed. Most tumors have clear cell histologic features, and the amyloid distribution follows the "secondary" pattern. A possible mechanism of amyloid production in renal cell carcinoma is presented in which the tumor directly or indirectly participates in the modification of SAA protein into a precipitable form.