title: Cytopathologic features of clear cell papillary renal cell carcinoma: A recently described variant to be considered in the differential diagnosis of clear cell renal epithelial neoplasms.
abstract: BACKGROUND
  Clear cell papillary renal cell carcinoma (CCPRCC) is a distinctive variant of renal cell carcinoma that has been formally adopted by the new Word Health Organization classification. An emerging consensus has documented its particularly indolent course and emphasized its separation from conventional clear cell renal cell carcinoma (CCRCC) for treatment planning. CCPRCC features in cytologic preparations have not been studied.
  
  
  METHODS
  This study retrospectively identified a series of CCPRCCs that had cytology samples before the histopathologic diagnosis and reviewed corresponding cytologic materials, including aspirate smears, cell block materials, touch preparations, and core biopsy samples. The identified clinicopathologic and cytologic features were tabulated.
  
  
  RESULTS
  Five cases of CCPRCC with cytopathologic materials were identified from 4 women and 1 man aged 34 to 70 years (2 with end-stage renal disease), and the sampled lesions were 1.8 to 11.0 cm. The original cytopathologic diagnostic considerations ranged from atypical cyst-lining cells to angiomyolipoma to CCRCC and CCPRCC. The aspirate and touch preparation samples showed scant cellularity with scattered sheets and clusters of small, bland epithelial cells (much smaller than admixed renal tubular cells) with optically clear cytoplasm (lacking conspicuous cytoplasmic vacuolization) and small, grade 1 nuclei. The cell block materials and the core biopsy samples showed cyst walls with prominent myomatous stroma lined by low-grade epithelium with optically clear cytoplasm, inverse nuclear polarization, and a characteristic cytokeratin 7-positive/carbonic anhydrase IX-positive phenotype. Three cases were treated with resection, 1 case was treated with ablation, and 1 case was under surveillance.
  
  
  CONCLUSIONS
  CCPRCC demonstrates recognizable cytomorphologic features and merits consideration in the cytologic differential diagnosis for kidney lesions. With increasing experience, more conservative management may be contemplated. Cancer Cytopathol 2016;124:565-72. © 2016 American Cancer Society.
authors.affiliation: Department of Pathology, Virginia Commonwealth University Health System, Richmond, Virginia.
authors.forename: Sadia
authors.initials: S
authors.lastname: Sayeed
authors.affiliation: Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina.
authors.forename: Kathryn G
authors.initials: KG
authors.lastname: Lindsey
authors.affiliation: Department of Pathology, Johns Hopkins University, Baltimore, Maryland.
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Baras
authors.affiliation: School of Medicine, Virginia Commonwealth University Health System, Richmond, Virginia.
authors.forename: Christopher
authors.initials: C
authors.lastname: Jackson
authors.affiliation: Department of Pathology, Virginia Commonwealth University Health System, Richmond, Virginia.
authors.forename: Celeste N
authors.initials: CN
authors.lastname: Powers
authors.affiliation: Department of Pathology, Virginia Commonwealth University Health System, Richmond, Virginia.
authors.forename: Cora
authors.initials: C
authors.lastname: Uram-Tuculescu
authors.affiliation: Department of Pathology, Virginia Commonwealth University Health System, Richmond, Virginia.
authors.forename: Steven C
authors.initials: SC
authors.lastname: Smith
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis*; D002291:Carcinoma, Papillary / Q000473:pathology*; D002292:Carcinoma, Renal Cell / Q000473:pathology*; D003937:Diagnosis, Differential; D004847:Epithelial Cells / Q000473:pathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007680:Kidney Neoplasms / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009361:Neoplasm Invasiveness; D011379:Prognosis; D011446:Prospective Studies; D012189:Retrospective Studies
chemical_list: D014408:Biomarkers, Tumor
keywords: aspiration cytology; clear cell papillary renal cell carcinoma; clear cell renal cell carcinoma; immunohistochemistry