title: Cytomorphology of clear cell papillary renal cell carcinoma.
abstract: BACKGROUND
  Clear cell papillary renal cell carcinoma (CCPRCC) shares some morphologic and immunohistochemical markers with clear cell RCC and papillary RCC. To the author's knowledge, its cytomorphology on fine-needle aspiration (FNA) or touch preparations (TPs) of core needle biopsy specimens has not been well delineated in the English language literature.
  
  
  METHODS
  The FNA/TP cytomorphology of 7 retrieved cases was studied.
  
  
  RESULTS
  The tumor cells were arranged in small nests (100%), 3-dimensional clusters (71%), papillary/tubular/acinar arrays (43%), and as single cells (57%). The tumor cells were columnar (100%) and polygonal (57%) in shape, with eccentric, small, round-to-oval nuclei. The nuclei contained evenly distributed, fine granular chromatin and demonstrated a smooth nuclear membrane (100%) (Fuhrman grade 1 to 2). The tumor cells had a moderate amount of delicate or clear cytoplasm containing small vacuoles (100%) and ill-defined cytoplasmic borders (100%). Scattered macrophages (57%) and necrosis (29%) were identified in the background. Vessels were noted within the papillary cores, transversing or surrounding nests of tumors. Immunochemical studies demonstrated expression of cytokeratin 7 (CK7) (100%), carbonic anhydrase IX (CA 9) (100% in a cup-shaped membranous pattern), α-methylacyl-CoA racemase (AMACR) (50%), and CD10 (43%). The tumor cells were negative for CD117.
  
  
  CONCLUSIONS
  CCPRCC was found to demonstrate cytologic features that when taken together are helpful in diagnosing CCPRCC on FNA smears and TPs. If core needle biopsy specimens or cell blocks are available, an immunohistochemical panel including CK7, CA IX, CD10, and AMACR may help in excluding congeners. This subtype of RCC requires differentiation from clear cell RCC and papillary RCC due to its low-grade indolent behavior. Cancer Cytopathol 2017;125:48-54. © 2016 American Cancer Society.
authors.affiliation: Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois.
authors.forename: Xiaoqi
authors.initials: X
authors.lastname: Lin
mesh_terms: D000328:Adult; D000368:Aged; D000951:Antigens, Neoplasm / Q000235:genetics; D014408:Biomarkers, Tumor / Q000235:genetics*; D044963:Biopsy, Fine-Needle; D000071231:Carbonic Anhydrase IX / Q000235:genetics; D002292:Carcinoma, Renal Cell / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D053552:Keratin-7 / Q000235:genetics; D008297:Male; D008875:Middle Aged; D015260:Neprilysin / Q000235:genetics; D019998:Racemases and Epimerases / Q000235:genetics
chemical_list: D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D053552:Keratin-7; D015260:Neprilysin; C089226:CA9 protein, human; D000071231:Carbonic Anhydrase IX; D019998:Racemases and Epimerases; C108352:alpha-methylacyl-CoA racemase
keywords: clear cell papillary renal cell carcinoma; core needle biopsy; cytomorphology; fine-needle aspiration; immunohistochemistry; touch preparation