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Abstract: SA-PO1022

A Report on Multifocal Bilateral Renal Oncocytomas Leading to Interstitial Nephritis

Session Information

Category: Nephrology Education

  • 1302 Fellows and Residents Case Reports


  • Malhotra, Divyanshu, Yale New Haven Hospital, New Haven, Connecticut, United States
  • Luciano, Randy L., Yale University School of Medicine, New Haven, Connecticut, United States

Renal oncocytomas are benign tumors originating from the intercalated cells of the collecting duct. They are rare, with an incidence of up to 7% of all renal tumors. The majority of tumors are solitary, but up to 12% can be multifocal with 4-12% being bilateral. These are often found incidentally, but on occasion flank pain or hematuria are presenting signs. Less is known about the nature of multifocal bilateral oncocytomas and their renal complications. Here we present two patients with multifocal bilateral oncocytomas with associated interstitial nephritis.


The first patient is a 44 year old gentleman with no significant medical history who was found to have multifocal renal tumors on CT scan that was performed after the discovery of hematuria. Biopsy showed multiple oncocytomas with a surrounding dense interstitial infiltrate. Clinically the patient had a serum creatinine of 1.5 mg/dL with no underlying medications or co-morbid conditions that could be attributed to the interstitial inflammation.
The second patient is a 72 year old gentleman with a history of treated prostate cancer and well controlled hypertension who had multifocal kidney lesions identified on CT scan when he was diagnosed with prostate cancer. Biopsy revealed a dense interstitial infiltrate in tissue adjacent and away from the encapsulated lesions. No medications or disease could explain the interstitial nephritis. Clinically his creatinine has increased steadily from 1.8 mg/dL to 2.7 mg/dL over the last five years.


Renal oncocytomas are rare but potentially important tumors. Diagnosis through histology is important because they can appear similar to malignant renal tumors. Pathological examination reveals a well-circumscribed collection of oncocytes with a central scar, devoid of necrosis or vascular inflammation. Treatment usually consists of radical or partial nephrectomy versus observation, and prognosis is excellent. Both of these patients demonstrate the importance of diagnosing renal involvement in patients with multifocal oncocytomas. Since surgery is not possible for these multifocal and bilateral kidney lesions, it is necessary to monitor these patients closely with the possibility of medically treating the underlying inflammation if unexplained rises in creatinine ensue.