Renal oncocytoma, yet another tumour that does not fit in the dualistic benign/malignant paradigm?
- Department of Pathology, University Health Network, Toronto, Ontario, Canada
- Correspondence to: Professor T H Van der Kwast Department of Pathology, University Health Network, Toronto General Hospital, 610 University Avenue, Toronto, Ontario, Canada M5G 2M9; theo.vdkwast{at}uhn.on.ca
- Accepted 12 January 2007
A debate on whether renal oncocytomas are benign neoplasms or malignant tumours See case report, p 720
Since its original description in 1942 and its establishment as a distinct entity in 1976, the metastatic potential of renal oncocytoma has been the subject of considerable controversy. Throughout the years, several reports have claimed a low metastatic potential for these tumours, yet the debate remains. The 2004 World Health Organization1 classification of renal tumours categorises renal oncocytomas as benign neoplasms. One of the reasons for this debate is that renal oncocytomas may be confused with clear cell renal carcinomas with a dominant eosinophilic component and—a more difficult differential diagnosis—with the eosinophilic variant of chromophobe renal cell carcinoma, a tumour with recognised low metastatic potential. The latter entity was first described by Thoenes et al2 in 1985, although general recognition of this lesion had to wait for another 5 years. This may have delayed the awareness of potential confusion between chromophobe renal cell carcinoma and renal oncocytoma. In a large study of 166 oncocytomas published in 1991, the differential diagnosis of chromophobe carcinoma was not mentioned, although the authors recognised granular cell carcinoma as a potential source of misdiagnosis.3 …
