Clear cell papillary renal cell carcinoma and clear cell renal cell carcinoma arising in acquired cystic disease of the kidney: an immunohistochemical and genetic study Naoto Kuroda, MD a, ⁎ , Tomoyuki Shiotsu, MD b , Chiaki Kawada, MSc c , Taro Shuin, MD c , Ondrej Hes, MD d , Michal Michal, MD d , Chisato Ohe, MD e , Shuji Mikami, MD f , Chin-Chen Pan, MD g a Department of Diagnostic Pathology, Kochi Red Cross Hospital, Kochi, Japan b Department of Urology, Kochi Red Cross Hospital, Kochi, Japan c Department of Urology, Kochi Medical School, Kochi University, Kochi, Japan d Department of Pathology, Charles University Hospital Plzen, Plzen, Czech Republic e Department of Pathology, Kansai Medical University Hirakata Hospital, Osaka, Japan f Division of Diagnostic Pathology, Keio University Hospital, Tokyo, Japan g Department of Pathology, Taipei Veterans General Hospital, Taipei, Taiwan Abstract Clear cell papillary renal cell carcinoma (RCC) is a recently established disease entity. However, there are few reports on genetic study of this entity. We report such a case with focus on genetic study. A 57-year-old Japanese man was found to have 3 renal tumors. Histologically, two tumors showed findings of clear cell RCC; and the other tumor showed findings of clear cell papillary RCC that was characterized by papillary growth pattern of neoplastic cells in cystic space with purely clear cell cytology. Immunohistochemically, tumor cells of clear cell papillary RCC were diffusely positive for PAX2 and cytokeratin 7, but negative for CD10, RCC Ma, and AMACR. In fluorescence in situ hybridization study for one clear cell papillary RCC, we detected polysomy for chromosome 7 and monosomy for chromosomes 17, 16, and 20. In addition, we detected mutation of VHL gene in clear cell RCC, but found no VHL gene mutation in clear cell papillary RCC. Finally, our results provide further evidence that clear cell papillary RCC may be both morphologically and genetically distinct entity from clear cell RCC and papillary RCC. © 2011 Elsevier Inc. All rights reserved. Keywords: Clear cell papillary renal cell carcinoma; VHL gene; FISH 1. Introduction The concept of clear cell papillary renal cell carcinoma (RCC) has been recently established as a genetically defined entity, with distinct morphology, different from clear cell RCC or papillary RCC; and studies on this tumor are limited [1,2]. To the best of our knowledge, there are no VHL gene analyses on clear cell papillary RCC available in the literature. We report here a case of clear cell RCC and clear cell papillary RCC arising in acquired cystic disease kidney. In this article, we report the VHL gene mutation analysis for clear cell papillary RCC and clear cell RCC and fluorescence in situ hybridization (FISH) analysis for clear cell papillary RCC and discuss the significance of this tumor entity. 2. Case report A 57-year-old Japanese man has received peritoneal dialysis for 6 years and hemodialysis for 8 years because of chronic renal failure due to chronic glomerulonephritis. A follow-up computed tomography scan/magnetic resonance imaging disclosed the renal tumors in the left kidney. Subsequently, left nephrectomy was performed. His clinical course was uneventful 35 months postoperatively. Available online at www.sciencedirect.com Annals of Diagnostic Pathology 15 (2011) 282 – 285 ⁎ Corresponding author. Tel.: +81 88 822 1201; fax: +81 88 822 1056. E-mail address: kurochankochi@yahoo.co.jp (N. Kuroda). 1092-9134/$ – see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.anndiagpath.2010.03.007