[836] Renal Epithelial Tumors with Clear Cell Morphology Encompass a Heterogeneous Group of Renal Cell Carcinomas.

Mojgan Hosseini, Maria Tretiakova, Anthony Chang, Jerome Taxy, Tatjana Antic. University of Chicago, IL

Background: Clear cell renal cell carcinoma (CRCC) is the most common kidney malignancy. In recent years, immunohistochemistry (IHC) and molecular methods have identified other new entities with clear cell morphology, e.g., clear cell papillary (CPRCC) and translocation RCC (TRCC), mostly in young patients. This study investigated the occurrence of these entities among cases previously diagnosed as RCC.
Design: A review of surgical pathology archives from 2005-2010 revealed 109 cases of RCC in individuals 20-50 years of age. Based on morphology 13 were chromophobe RCC, 21 papillary, 1 medullary and 1 adult Wilms. 27 cases were not available for review and 46 had clear cell morphology. The H&E sections were reviewed and supplemented by an IHC panel of AMACR, TFE3, CK7 and CAIX.
Results: The original diagnoses in the 46 cases were: 41 CRCC, 4 TRCC and 1 case unclassified. The revised interpretations based on morphology and IHC profile were: 27 CRCC, 5 CPRCC, 12 TRCC and 2 unclassified RCC. Of the 27 CRCC cases, 12 were AMACR, TFE3 and CK7 negative, positive for CAIX; 9 were AMACR and CAIX positive, negative for CK7 and TFE3; 6 were AMACR, CK7 and CAIX positive, TFE3 negative. Of the 5 CPRCC cases, all were AMACR and TFE3 negative, positive for CK7 and CAIX. All 12 TRCC were TFE3 positive but only 10 and 9 were positive for AMACR and CAIX respectively. Of the 2 unclassified cases, both demonstrated TRCC morphology; however they were negative for TFE3 and positive for CAIX.
Conclusions: Clear cell morphology is not restricted to conventional CRCC as the newly described entities of CPRCC and TRCC demonstrate. A histologic and IHC review of 46 clear cell tumors in patients ranging from 20-50 years old within a 5 year period resulted in a change of diagnosis in 12 cases (26%) to the newly described entities. The potential heterogeneity of CRCC is presently of uncertain clinical significance, although the subtypes do affect a younger population. In addition, the reported evolution of these clear cell carcinoma subtypes suggests a more indolent course for PCRCC and more aggressive for TRCC. Awareness of these entities as supplemented by immunostaining may impact the implementation of partial nephrectomy, non surgical treatments and focused clinical surveillance.
Category: Genitourinary (including renal tumors)

Wednesday, March 2, 2011 9:30 AM

Poster Session V # 83, Wednesday Morning


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