[1021] The Utility of SF-1 and Cathepsin K as Differentiating Immunohistochemical Markers in Adrenal Cortical Carcinoma and Epithelioid Angiomyolipoma

Teresa D Samulski, Shuting Bai, Amberly L Nunez, Shi Wei, Liping Wang, Zhanyong Bing. Hospital of the University of Pennsylvania, Philadelphia, PA; New York University, New York, NY; University of Alabama, Birmingham, AL

Background: Distinguishing primary tumors of the kidney and adrenal gland can at times be challenging. This is especially true in cases that share morphologic and immunhistochemical characteristics, such as those cases of adrenal cortical carcinoma and epithelioid variant of angiomyolipoma (EAML); two rare, yet aggressive tumors. We explore the diagnostic utility of immunohistochemical staining for SF-1 and cathepsin K in combination for differentiating these two distinct neoplasms.
Design: Fourteen cases of EAML were stained with cathepsin K and steroidogenic factor (SF-1) antibodies. 20 cases of adrenal cortical carcinoma (in tissue microarray) were also stained with cathepsin K antibody. Staining in all cases was evaluated and scored for intensity (0, negative; 1, weak intensity; 2, moderate intensity; 3, strong intensity) and extent of immunoreactivity (0, negative; 1, <30%; 2, 30-70%; 3, >70%). The final scores were achieved by the sum of intensity and extent of immunoreactivity divided by two.
Results: Staining for cathepsin K in cases of epithelioid angiomyolipoma resulted in an average score of 2.8+/-0.3, comparable to an average score of 2.8+/-0.2 in cases of andrenal cortical carcinoma. Cases of EAML failed to demonstrate staining for SF-1, with an average score of 0. This is in contrast to SF-1 staining in adrenal cortical carcinoma. We have demonstrated previously that all adrenal cortical carcinomas showed strong nuclear staining for SF-1.
Conclusions: In our experience, staining for cathepsin K and SF-1 was a concise panel in differentiating EAML and adrenal cortical carcinoma, in which both EAML and adrenal cortical carcinoma showed strong positivity for cathepsin K, yet only adrenal cortical carcinoma showed strong positivity for SF-1, while EAML was negative for this factor.
Category: Genitourinary (including renal tumors)

Wednesday, March 6, 2013 9:30 AM

Poster Session V # 161, Wednesday Morning

 

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