Differentiating Chromophobe Renal Cell Carcinoma from Oncocytomas: Utility of a Novel Immunomarker, Amylase 1A
Sarika Jain, Milon Amin, Somak Roy, Marie Acquafondata, William LaFramboise, Sheldon Bastacky, Rajiv Dhir, Anil Parwani. University of Pittsburgh Medical Center, Pittsburgh, PA
Background: Chromophobe renal cell carcinoma (Ch-RCC) and Oncocytoma are distinct renal tumors with a common origin: the intercalated cell of the collecting duct. Both tumors present with a perplexing overlap of morphological and immunohistochemical (IHC) features. Unfortunately, no biomarker specifically aids in this distinction; yet, distinction is needed because clinical outcomes are signficantly different. A recent study from our institution (Krill-Burger et al. Am J Pathol 2012;180:2427) demonstrated deletion in 1p21.1 region in Ch-RCCs. AMY1A as one of the genes in this region. Our aim was to assess the utility of AMY1A as a diagnostic biomarker for oncocytoma.
Design: IHC staining was performed on whole slide sections of 14 oncocytomas and 21 Ch-RCC using an anti-AMY1A antibody (Abnova, clone 2D4, monoclonal). Tissue microarrays (TMAs) consisting of oncocytoma (n=57), chromophobe RCC (n=9), normal kidney, and various other normal organs were also assessed by IHC. Staining was assessed using H-score method (stain intensity x percentage of cells positive for each intensity score). Staining intensity was graded as no staining=0, weak = 1, moderate=2 and strong =3.
|AMY1A (Staining Intensity)|
|Oncocytoma (n=71)||0 (0%)||10 (14%)||25 (35%)||36 (51%)|
|Chromophobe RCC (n=30)||25 (83%)||5 (17%)||0 (0%)||0 (0%)|