title: Diffuse and strong cyclin D1 immunoreactivity in clear cell sarcoma of the kidney.
abstract: OBJECTIVE
  Distinguishing clear cell sarcoma of the kidney (CCSK) from other paediatric malignancies, particularly blastema-rich Wilms tumour (WT) and congenital mesoblastic nephroma (CMN), is challenging. Specific immunohistochemistry for CCSK does not exist, and diagnosis rests upon histopa thology. Recently, the YWHAE-FAM22 rearrange ment, identical to that in endometrial stromal sarcoma (ESS), has been identified in CCSKs. As this fusion results in overexpression of cyclin D1 in ESS, we postulated that overexpression would also occur in CCSK; cyclin D1 immunohistochemistry could then be used to differentiate CCSK from other tumours. The goal of this study was therefore to evaluate the utility of cyclin D1 immunohistochemistry in identifying CCSK and helping to differentiate it from its mimics.
  
  
  RESULTS
  Cyclin D1 expression was evaluated in 59 renal tumours-CCSK (14), WT (25), rhabdoid tumour (four), Ewing sarcoma (five), and CMN (11)-and four neuroblastomas. All 14 CCSKs showed diffuse and strong reactivity. In contrast, the blastematous component of most WTs showed only rare positive nuclei, that of rhabdoid tumours showed rare to focal immunoreactivity, and that of more than half of CMNs showed weak or focal immunoreactivity. Most Ewing sarcomas and all neuroblastomas showed diffuse moderate to strong staining.
  
  
  CONCLUSIONS
  Cyclin D1 is most helpful in distinguishing CCSK from WT, rhabdoid tumour, and some CMNs, but not from neuroblastoma or Ewing sarcomas.
authors.affiliation: Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA.|Department of Pathology, Boston Children's Hospital, Boston, MA, USA.|Harvard Medical School, Boston, MA, USA.
authors.forename: Jelena
authors.initials: J
authors.lastname: Mirkovic
authors.affiliation: Department of Pathology, Boston Children's Hospital, Boston, MA, USA.
authors.forename: Monica
authors.initials: M
authors.lastname: Calicchio
authors.affiliation: Department of Pathology, Brigham and Women's Hospital, Boston, MA, USA.|Harvard Medical School, Boston, MA, USA.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Fletcher
authors.affiliation: Department of Pathology, Boston Children's Hospital, Boston, MA, USA.|Harvard Medical School, Boston, MA, USA.
authors.forename: Antonio R
authors.initials: AR
authors.lastname: Perez-Atayde
mesh_terms: D014408:Biomarkers, Tumor / Q000378:metabolism; D002675:Child, Preschool; D019938:Cyclin D1 / Q000378:metabolism*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007680:Kidney Neoplasms / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology*; D008297:Male; D018201:Nephroma, Mesoblastic / Q000175:diagnosis / Q000378:metabolism; D009447:Neuroblastoma / Q000175:diagnosis / Q000378:metabolism; D018335:Rhabdoid Tumor / Q000175:diagnosis / Q000378:metabolism; D018227:Sarcoma, Clear Cell / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology*; D012512:Sarcoma, Ewing / Q000175:diagnosis / Q000378:metabolism; D009396:Wilms Tumor / Q000175:diagnosis / Q000378:metabolism
chemical_list: D014408:Biomarkers, Tumor; C530104:CCND1 protein, human; D019938:Cyclin D1
keywords: Ewing sarcoma; Wilms tumour; children; cyclin D1; mesoblastic nephroma; renal clear cell sarcoma; rhabdoid tumour