Incidence of Clear Cell Papillary Renal Cell Carcinoma in Low-Grade Renal Cell Carcinoma Cases

Abstract

Clear cell papillary renal cell carcinoma (CCPRCC) is a recently recognized subtype of renal cell carcinoma entity after 2004 World Health Organization classification of renal tumors. CCPRCC has unique histomorphological and immunohistochemical characteristics. The distinction of CCPRCC from renal cell carcinoma (RCC) with clear cell morphology is crucial because the former is considered to have a favorable clinical outcome. CCPRCC may be interpreted in the past as other renal cell carcinomas, particularly low-grade clear cell RCC. In this study, the frequency of CCPRCC in previously diagnosed low-grade RCC and its clinicopathologic features were examined. A total of 126 cases of stage T1a with low nuclear grade RCC were identified from 625 consecutive RCCs removed by radical/partial nephrectomy over 12-year period (2000-2011). Archival tissue sections were retrospectively reviewed along with patient medical charts. Eight cases (1.3% of all RCC, 6.3% of pT1a low grade RCC) with characteristic histologic features of CCPRCC were confirmed by immunohistochemical studies. Seven cases were previously diagnosed as clear cell RCC and one as multilocular cystic RCC. Radiographically, CCPRCC favored a mid-pole location in the kidneys. At a median follow-up period of 52 months (range 20-114.5 months), there were no cases of local or distant recurrence. In conclusion, CCPRCC is not uncommon among small low-grade RCC tumors. CCPRCC can be correctly recognized by its unique histomorphological features and confirmed by immunohistochemistry studies, which is important due to the excellent clinical outcome following resection.

Cytomorphology of clear cell papillary renal cell carcinoma

“…However, the most characteristic morphological feature is the positioning of the small round nuclei within the cells away from the basement membrane, imparting an appearance reminiscent of secretory endometrium or papillary cystadenoma of the epididymis and broad ligament . These tumors originally were described within the setting of end‐stage renal disease, but are now widely recognized to occur outside of this setting . It is the fourth most common histologic subtype of RCC, representing 1.3% to 4.3% of all RCC cases, and comprising 6.3% of pT1a, low‐grade RCC .…”

“…5 These tumors originally were described within the setting of end-stage renal disease, but are now widely recognized to occur outside of this setting. 4,[6][7][8][9][10] It is the fourth most common histologic subtype of RCC, 8 representing 1.3% to 4.3% of all RCC cases, and comprising 6.3% of pT1a, low-grade RCC. 4,[6][7][8][9][10] Patient ages range from 33 to 87 years, 9 and the disease is distributed equally among both sexes.…”

Clear cell renal cell carcinoma with wild‐type von Hippel‐Lindau gene: a non‐existent or new tumour entity?

“…It is thought that these subtypes of RCC are not rare, and cases are present around the world which are simply not recognised. CCPRCC is thought to have a prevalence rate of approximately 1–4% and that approximately 6% of low‐grade ccRCC are, in fact, CCPRCC . Furthermore, following immunohistochemical and fluorescence in‐situ hybridisation (FISH) analysis, few RAT cases have been reclassified to translocation RCC (tRCC).…”

“…CCPRCC is thought to have a prevalence rate of approximately 1-4% and that approximately 6% of low-grade ccRCC are, in fact, CCPRCC. 40,41 Furthermore, following immunohistochemical and fluorescence in-situ hybridisation (FISH) analysis, few RAT cases have been reclassified to translocation RCC (tRCC). tRCC are characterised by chromosomal translocations of Xp11.2, the location of TFE3 and, less frequently, 6p21, the location of TFEB, 39 but are not associated with VHL inactivation.…”

A contemporary series of renal masses with emphasis on recently recognized entities and tumors of low malignant potential: A report based on 624 consecutive tumors from a single tertiary center

“…However, some authorities consider current experience limited to supporting these neoplasms as benign entities. The experience on this tumor ranges from a few cases reported, to about 200 cases, but CCPRCC is recognized as the most common within the low malignant category [19][20][21].…”