title: WT1 marker is not sufficient for distinguishing between melanoma and melanocytic nevi.
abstract: BACKGROUND
  The heterogeneous histological features of melanoma may often overlap with melanocytic nevi. For this reason, pathologists have sought after immunohistochemistry to assist with difficult cases. Recently, Wilms' tumor 1 protein (WT1) has been suggested to differentiate between melanoma and melanocytic nevi.
  
  
  OBJECTIVE
  Our objective was to determine whether immunohistochemistry analysis of WT1 expression is a reliable tool in differentiating cutaneous melanoma from melanocytic nevi.
  
  
  METHODS
  Forty-five melanoma and 43 melanocytic nevi were immunostained with anti-WT1 monoclonal antibody (clone 6F-H2).
  
  
  RESULTS
  Forty of the 45 cutaneous melanoma (89%) and 22 of the 43 melanocytic nevi (51%) stained (> 10% cells) for WT1. The highest sensitivity for WT1 was expressed by nodular melanoma (19/20), superficial spreading melanoma (8/10) and Spitz nevi (9/11). At the threshold of above 75% WT1-stained cells, the specificity for melanoma was 95% but the sensitivity was only 31%. At the threshold of 10%, the sensitivity increased to 89% but the specificity decreased to only 49%. Finally, at the threshold of 25% and 50%, the sensitivity and specificity were 71%, 61% and 64%, 77%, respectively.
  
  
  CONCLUSIONS
  Our data suggest that melanoma is associated with increased WT1 expression. However, as a single immunostaining marker, WT1 is not sufficient for distinguishing melanoma from melanocytic nevi.
authors.affiliation: Laboratory for Molecular Dermatology, Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI 48201, USA. krosner@med.wayne.edu
authors.forename: Karli
authors.initials: K
authors.lastname: Rosner
authors.forename: Darius R
authors.initials: DR
authors.lastname: Mehregan
authors.forename: Darius
authors.initials: D
authors.lastname: Moussai
authors.forename: Judith
authors.initials: J
authors.lastname: Abrams
authors.forename: Gerard
authors.initials: G
authors.lastname: Tromp
authors.forename: David A
authors.initials: DA
authors.lastname: Mehregan
mesh_terms: D000368:Aged; D000911:Antibodies, Monoclonal; D014408:Biomarkers, Tumor / Q000032:analysis*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008545:Melanoma / Q000473:pathology*; D008875:Middle Aged; D009508:Nevus, Pigmented / Q000473:pathology*; D012680:Sensitivity and Specificity; D012878:Skin Neoplasms / Q000473:pathology*; D025721:WT1 Proteins / Q000096:biosynthesis*
chemical_list: D000911:Antibodies, Monoclonal; D014408:Biomarkers, Tumor; D025721:WT1 Proteins