title: Cytohistopathologic hybrid renal cell carcinoma with papillary and clear cell features.
abstract: Clear cell (CRCC) and papillary (PRCC) renal cell carcinomas (RCC) are the two most frequent subtypes of RCC. In this study, we studied RCC which displayed a hybrid morphology with areas of PRCC and CRCC or which contained papillary structures with clear cell changes (CCC). Consecutive cases of RCC collected over a 12-year period were reviewed to identify RCC with papillary structures and a possible admixture between CRCC and non-oncocytic PRCC. Special stains for glycogen and immunostaining for cytokeratin 7 were applied to sections containing both areas of classical PRCC and PRCC with CCC. Of the total of 541 RCC retrieved, there were 68 non-oncocytic RCC having papillary structures that could be grouped into: (a) group 1 (15 cases), CRCC with areas of papillary formation; (b) group 2a (9 cases), PRCC with extensive CCC with areas of foamy epithelial cells or macrophages; (c) group 2b (18 cases), RCC with areas of classical PRCC with focal CCC; and (d) group 3 (26 cases), RCC with features of groups 2a and 2b and containing areas of classical CRCC. There was a high rate (12/68) of sarcomatous transformation in the study cases. Groups 2 and 3 were associated with a higher rate of vascular invasion, distant metastasis, and mortality than classical PRCC and a higher rate of lymph node metastasis than CRCC. Our study identifies two groups of RCC (referred to as groups 2 and 3) that exhibit characteristic cytohistopathologic hybrid features that set them apart from classical RCC. This type of hybrid tumor seems to be associated with a more aggressive biologic behavior, and its recognition may facilitate the classification of RCC with ambiguous morphology.
authors.affiliation: Department of Pathology and Laboratory Medicine, The Ottawa Hospital and University of Ottawa, Ont., Canada. ktmai@ottawahospital.on.ca
authors.forename: Kien T
authors.initials: KT
authors.lastname: Mai
authors.forename: Derek M
authors.initials: DM
authors.lastname: Kohler
authors.forename: Nicolas L
authors.initials: NL
authors.lastname: Roustan Delatour
authors.forename: John P
authors.initials: JP
authors.lastname: Veinot
mesh_terms: D018262:Adenocarcinoma, Clear Cell / Q000737:chemistry / Q000401:mortality / Q000556:secondary*; D000231:Adenocarcinoma, Papillary / Q000737:chemistry / Q000401:mortality / Q000556:secondary*; D014408:Biomarkers, Tumor / Q000032:analysis; D002170:Canada / Q000453:epidemiology; D002292:Carcinoma, Renal Cell / Q000737:chemistry / Q000401:mortality / Q000556:secondary*; D006003:Glycogen / Q000032:analysis; D006801:Humans; D007124:Immunoenzyme Techniques; D053552:Keratin-7 / Q000032:analysis; D007680:Kidney Neoplasms / Q000737:chemistry / Q000401:mortality / Q000473:pathology*; D015996:Survival Rate
chemical_list: D014408:Biomarkers, Tumor; D053552:Keratin-7; D006003:Glycogen