Histogenesis of renal cell carcinoma and renal oncocytoma: An immunohistochemical study

The histogenesis of renal cell carcinoma and oncocytoma is controversial. We compared immtinohistochemical profiles of normal kidney, nine carcinomas, and six oncocytomas. Carcinomas and oncocytomas expressed the following antigens respectively: proximal tubule—Uro 3 (56 & 67%), alpha‐1‐antitrypsin (89 & 50%); proximal and distal tubule—Uro 10 (67 & 83%); distal tubule—B2‐microglobulin (100 & 100%); distal/medullary tubule‐epithelial membrane antigen (89 & 83%), neuron‐specific enolase (78 & 100%), glandular cytokeratin (78 & 100%), epidermal keratin (67 & 67%); and medullary tubule—Uro 8 (89 & 83%). All tumors, except one oncocytoma, had at least one positive reaction for each antigen group. Oncocytomas predominantly stained for distal/medullary tubular antigens; none showed a predominance of proximal tubular antigens. Carcinomas also demonstrated largely distal/medullary tubule antigens; 44% showed prominence of proximal tubular antigens as well. Assignment of an exclusive proximal, distal or medullary tubule origin to renal neoplasms does not appear valid. Divergent histogenesis from a precursor stem cell is likely.