Expression of epidermal growth factor receptor and proliferative activity of cyst epithelium in human renal cystic diseases.

Pathogenesis of malignancies in patients with polycystic kidney disease (PKD) is not clearly understood. Epidermal growth factor receptor (EGF-r) production by mature kidney plays a role in promotion of epithelial hyperplasia and cyst formation, its involvement in further progression is however not proven. Ki-67 is a marker for cellular proliferation. We assessed immunohistochemical expression of EGF-r and Ki-67 in epithelium of normal kidney, single cysts without PKD, epithelial tubular cells lining simple cysts and cysts with papillary proliferation in PKD patients, and analyzed the relationship with the occurrence of malignant tumors in these cases. 72% of PKD displayed EGF-r staining in epithelium lining cysts versus 33% in normal epithelium and 70% in epithelium of normal kidney. Ki-67 was increased in papillary cystic epithelium (24%) and in cysts lined by flat epithelium (66%). Renal cancers in PKD showed EGF-r staining in 33%, but no Ki-67 expression. EGF-r function and proliferative activity in cyst formation in PKD remains to be explored. EGF-r and Ki-67 expressions are not predictive of development of carcinoma in PKD.