[779] Oncocytic Tumors of the Kidney: Reappraisal of Histologic Spectrum and Clinical Behavior

H Aydin, B Lee, S Campbell, L Sercia, C Magi-Galluzzi, M Zhou. Cleveland Clinic, Cleveland

Background: Oncocytic tumors of the kidney (OT) represent a group of tumors derived from the intercalated cells of collecting ducts and include benign oncocytomas (Onco) and malignant chromophobe renal cell carcinoma (ChRCC). However, tumors with intermediate or overlapping histological features between Onco and ChRCC are not infrequent. Their pathologic features are not well studied and little is known about their clinical behavior.
Design: Radical or partial nephrectomy specimens from1988 to 2004 containing Onco, ChRCC or OT were reviewed and categorized as follows: 1-typical oncocytoma (Onco), 2-oncocytoma with atypical features (Onco-atyp, if an Onco has diffuse nuclear atypia, perinuclear halo, or extension into perirenal fat), 3-oncocytoma with ChRCC (Onco-ChRCC, if an Onco has a ChRCC component < 25% of the tumor), 4-hybrid oncocytic tumor (HOT, if a tumor has both Onco and ChRCC each accounting for >25% of the tumor), 5-oncocytic tumor not otherwise specified (OTNOS, if a tumor has histological features intermediate between Onco and ChRCC), 6-eosinophilic ChRCC (ChRCC-e, if the eosinophilic component is >50% of the tumor) and 7-classical ChRCC (ChRCC). Clinical outcomes were categorized as no evidence of disease (NED), alive with stable disease (ASD), new disease in the remaining or contralateral kidney (NEW), and died of unknown or unrelated cause (DEAD).
Results: 391 tumors were studied and included 171 (43.7%) Onco, 60 (15.3%) Onco-atyp, 9 (2.3%) Onco-ChRCC, 12 (3.1%) HOT, 33(8.4%) OTNOS, 33 (8.4%) ChRCC-e, and 73 (18.7%) ChRCC. None had skin adnexal tumors and 1 with HOT had spontaneous pneumothorax. Multifocal and bilateral disease was present in 60 (15.3%) and 51 (13.0%) of tumors respectively. Follow-up was obtained in 105/147 (71.4%) of tumors other than Onco and ChRCC for a mean length of 61.7 (range 1-212) months. 87 (82.6%) were NED, 4 (3.8%) were ASD (2 Onco-atyp and 2 ChRCC-e), 4 (3.8%) were NEW (1 Onco-atyp and 3 OTNOS), and 11 (10.5%) were DEAD. No patient developed metastasis or died of the disease.
Conclusions: In addition to the typical Onco and ChRCC, the oncocytic tumors of the kidney show a wide spectrum of histologic features inbetween. The majority behave in a benign fashion while a minority (3.8%) develop new tumors in the remaining or contralateral kidney. No metastasis or death due to disease is seen. Therefore, they should be considered as benign or indolent tumors with potential to develop multifocal or bilateral disease but not metastasis.
Category: Genitourinary (including renal tumors)

Monday, March 22, 2010 2:15 PM

Platform Session: Section A, Monday Afternoon


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