AMACR Positive Papillary Renal Adenomatosis and Multifocal Papillary Carcinoma in End Stage Renal Disease

Immunomarker α-methylacyl-coenzyme A racemase (AMACR), a protein involved in the metabolism of branched chain fatty acids was initially recognized in the evaluation of prostate cancer. AMACR is also a fairly sensitive marker for papillary renal cell carcinoma. Papillary adenoma associated with papillary renal cell carcinoma are AMACR positive and both represent a continuum of the same biological process. However, the papillary adenomas associated with end-kidney and/or acquired cystic disease are AMACR negative. Herein, we report a case of AMACR positive renal adenomatosis with tiny foci of papillary carcinoma in a background of end stage kidney disease and nephrolithiasis. AMACR staining pattern in renal papillary adenomas needs more evaluation to better understand their pathogenesis under different settings.