[870] Clear Cell Cysts in Acquired Cystic Disease Represent an Early Lesion of Clear Cell Carcinoma

M Hosseini, T Antic, JB Taxy, A Chang. University of Chicago, Chicago, IL

Background: Acquired cystic disease (ACD) is common in patients with end-stage renal disease who are on dialysis. The cysts are often lined by clear cells. Given the significant increased risk of renal cell carcinoma (RCC) in these patients, these cysts may represent precursor lesions to the development of RCC. This study is conducted to determine the incidence and significance of clear cell lined cysts in the setting of ACD.
Design: A search of pathology archives from 2007-2009 identified 17 cases of native nephrectomies with end-stage renal disease and ACD. The specimens were carefully evaluated by light microscopy with an emphasis on the cysts and cystic lesions. Standard immunohistochemistry for carbonic anhydrase IX (CAIX, NCL-L-CAIX, Leica) was performed on cysts lined by epithelial cells with clear, foamy or eosinophilic cytoplasm.
Results: All 17 ACD cases contained multiple cysts (ranging from 0.1 to 4 cm in diameter). 7 cases (41%) showed strong (3+) membranous CAIX staining of the clear cell cysts (1-5 cysts per case). Adjacent cysts lined by epithelial cells with eosinophilic or foamy cytoplasm did not stain for CAIX. Of the 7 cases with CAIX positive clear cell cysts, 4 had at least two foci of RCC ranging in measurement from 0.2 to 4 cm. Three of 4 RCC contained a clear cell component, of which two were predominantly cystic. All had a Fuhrman grade of 1 or 2, and showed strong CAIX membranous staining. The fourth case had multiple microscopic foci (0.5 cm) of papillary RCC, which were not identified grossly. 6 additional cases containing cysts lined by epithelial cells with foamy cytoplasm were negative for CAIX staining. Of these 6 CAIX negative cases, 4 had papillary RCC and the other 2 had no carcinoma. 4 additional ACD cases had cysts lined with variable tufts of eosinophilic cuboidal epithelial cells, which did not stain with CAIX. Three of the cases with eosinophilic cuboidal epithelial lining cells had no cancer while one had a papillary RCC.
Conclusions: Clear cell cysts while few in number are common in ACD nephrectomy specimens. These cysts were present in all cases with clear cell carcinoma and a few cases without an obvious mass. These data support the idea that clear cell cysts represent the earliest neoplastic lesion of clear cell carcinomas. In ACD nephrectomy specimens with papillary RCC, only epithelial cells with eosinophilic or foamy cytoplasm but not clear cytoplasm were identified, suggesting a distinct line of tumorigenesis for papillary RCC.
Category: Genitourinary (including renal tumors)

Tuesday, March 23, 2010 9:30 AM

Poster Session III # 159, Tuesday Morning

 

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