Abstract
A 53-year-old woman who had been undergoing hemodialysis for 11 years was incidentally pointed out to have right renal tumor by abdominal echo and CT scanning in 1990. Subsequently, she had no symptomatic complaints and was followed up. She was, however, admitted to our hospital for further examinations of this tumor, though there was no recognizable tendency for growth on CT scan in 1992. It could not be ruled out that the tumor was a renal cell carcinoma on the basis of abdominal aortic angiography which showed moderate hypervascularity. She thus underwent right radical nephrectomy in April 1992. An operative specimen showed that, on light microscopy, the tumor was composed of oncocytic cells with abundant eosinophlic cytoplasm and there was an absence of significant nuclear pleomorphism. On electron microscopy, the cytoplasm of the oncocytic cells was characteristically filled with numerous mitochondria. These findings indicated renal oncocytoma. Only one other case of renal oncocytoma in a hemodialysis patient has been reported in Japan, to date, and the disease is considered to be rare.
