title: Achieving consensus for the histopathologic diagnosis of melanocytic lesions: use of the modified Delphi method.
abstract: OBJECTIVE
  To understand the sophisticated nature of coming to consensus when diagnosing complex melanocytic lesions among a panel of experienced dermatopathologists.
  
  
  METHODS
  A total of 240 melanocytic lesions were assessed independently by three experienced dermatopathologists with their diagnoses mapped into one of five Melanocytic Pathology Assessment Tool and Hierarchy for Diagnosis (MPATH-DX) categories: (I) nevus/mild atypia, (II) moderate atypia, (III) severe atypia/melanoma in situ, (IV) T1a invasive melanoma and (V) ≥ T1b invasive melanoma. The dermatopathologists then discussed the cases, using a modified Delphi method to facilitated consensus building for cases with discordant diagnoses.
  
  
  RESULTS
  For most cases, a majority of interpretations (two or three of three) agreed with the consensus diagnosis in 95% of Category I, 64% of Category II, 84% of Category III, 88% for Category IV and 100% of Category V cases. Disagreements were typically due to diagnostic threshold differences (64.5%), differing contents on slides even though the slides were sequential cuts (18.5%), and missed findings (15.3%). Disagreements were resolved via discussion of histopathologic features and their significance while reviewing the slides using a multi-headed microscope, considering treatment recommendations, citing existing literature, reviewing additional slides for a case, and choosing a provisional/borderline diagnosis to capture diverse opinions. All experienced pathologists participating in this study reported that the process of coming to consensus was challenging for borderline cases and may have represented compromise rather than consensus. They also reported the process changed their approaches to diagnosing complex melanocytic lesions.
  
  
  CONCLUSIONS
  The most frequent reason for disagreement of experienced dermatopathologists was differences in diagnostic thresholds related to observer viewpoints. A range of approaches was needed to come to consensus, and this may guide pathology groups who do not currently hold consensus conferences.
authors.affiliation: Professor of Family Medicine and of Public Health & Preventive Medicine, Oregon Health & Science University, Portland, OR, USA. carneyp@ohsu.edu.
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Carney
authors.affiliation: Department of Internal Medicine, University of Washington School of Medicine, Seattle, WA, USA.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Reisch
authors.affiliation: Division of Dermatology, Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA.|Dermatopathology Northwest, Bellevue, WA, USA.
authors.forename: Michael W
authors.initials: MW
authors.lastname: Piepkorn
authors.affiliation: Department of Pathology, University of California, Los Angeles, CA, USA.|Institut Curie and University of Paris Réne Descartes, Paris, France.
authors.forename: Raymond L
authors.initials: RL
authors.lastname: Barnhill
authors.affiliation: Department of Pathology, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: David E
authors.initials: DE
authors.lastname: Elder
authors.affiliation: Department of Pathology, The Veterans Affairs Medical Center, Seattle, WA, USA.|Assistant Professor of Pathology, University of Washington, Seattle, WA, USA.|Pathology Associates, Clovis, CA, USA.
authors.forename: Stevan
authors.initials: S
authors.lastname: Knezevich
authors.affiliation: Department of Family Medicine, University of Vermont, Burlington, VT, USA.
authors.forename: Berta M
authors.initials: BM
authors.lastname: Geller
authors.affiliation: Fred Hutchison Cancer Research Center, Seattle, WA, USA.
authors.forename: Gary
authors.initials: G
authors.lastname: Longton
authors.affiliation: Professor of Internal Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Joann G
authors.initials: JG
authors.lastname: Elmore
mesh_terms: D000328:Adult; D005260:Female; D016591:Histocytological Preparation Techniques / Q000379:methods* / Q000592:standards*; D006801:Humans; D008297:Male; D008545:Melanoma / Q000175:diagnosis*; D008875:Middle Aged; D012878:Skin Neoplasms / Q000175:diagnosis*
keywords: dermatopathology; interpretive accuracy; melanocytic lesions