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Pouwer AFW, Bult P, Otte I, van der Brand M, van der Horst J, Harterink LJV, van de Vijver KK, Guerra E, Aliredjo RP, Bosch SL, M M Grefte J, Zomer S, Hollema H, de Heus B, Satumalaij S, Ewing-Graham PC, IntHout J, de Hullu JA, Bulten J. Measuring the depth of invasion in vulvar squamous cell carcinoma: interobserver agreement and pitfalls. Histopathology 2019; 75:413-420. [PMID: 31021414 PMCID: PMC6851854 DOI: 10.1111/his.13883] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 04/22/2019] [Indexed: 11/28/2022]
Abstract
AIMS The depth of invasion is an important prognostic factor for patients with vulvar squamous cell carcinoma (SCC). The threshold of 1 mm distinguishes between FIGO stages IA and ≥IB disease and guides the need for groin surgery. Therefore, high interobserver agreement is crucial. The conventional and the alternative method are described to measure the depth of invasion. The aims of this study were to assess interobserver agreement for classifying the depth of invasion using both methods and to identify pitfalls. METHODS AND RESULTS Fifty slides of vulvar SCC with a depth of invasion approximately 1 mm were selected, digitally scanned and independently assessed by 10 pathologists working in a referral or oncology centre and four pathologists in training. The depth of invasion was measured using both the conventional and alternative method in each slide and categorised into ≤1 and >1 mm. The percentage of agreement and Light's kappa for multi-rater agreement were calculated, and 95% confidence intervals were calculated by bootstrapping (1000 runs). The agreement using the conventional method was moderate (κ = 0.57, 95% confidence interval = 0.45-0.68). The percentage of agreement among the participating pathologists using the conventional method was 85.0% versus 89.4% using the alternative method. Six pitfalls were identified: disagreement concerning which invasive nest is deepest, recognition of invasive growth and where it starts, curved surface, carcinoma situated on the edge of the tissue block, ulceration and different measurement methods. CONCLUSIONS Pathologists reached only moderate agreement in determining the depth of invasion in vulvar SCC, without a notable difference between the two measurement methods.
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Affiliation(s)
- Anne-Floor W Pouwer
- Department of Obstetrics and Gynaecology, Radboud University Medical Center, Radboud Institute of Health Sciences, Nijmegen, the Netherlands
| | - Peter Bult
- Department of Pathology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Irene Otte
- Department of Pathology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Michiel van der Brand
- Department of Pathology, Radboud University Medical Center, Nijmegen, the Netherlands
| | | | | | - Koen K van de Vijver
- Dienst Pathologische Anatomie, Laboratorium voor kankerdiagnostiek en pathologie, Universitair ziekenhuis Gent, Gent, Belgium
| | - Esther Guerra
- Department of Pathology, Hospital Universitari de Bellvitge, Barcelona, Spain
| | - Riena P Aliredjo
- Department of Pathology, Rijnstate Hospital, Arnhem, the Netherlands
| | - Steven L Bosch
- Laboratory for Pathology and Medical Microbiology (Stichting PAMM), Eindhoven, the Netherlands
| | | | - Saskia Zomer
- Department of Pathology, Canisius-Wilhelmina Hospital, Nijmegen, the Netherlands
| | - Harry Hollema
- Department of Pathology, University of Groningen - University Medical Center Groningen, Groningen, the Netherlands
| | - Barry de Heus
- Department of Pathology, University of Groningen - University Medical Center Groningen, Groningen, the Netherlands
| | - Saphira Satumalaij
- Department of Pathology, University of Groningen - University Medical Center Groningen, Groningen, the Netherlands
| | | | - Joanna IntHout
- Department of Health Evidence, Radboud University Medical Center, Institute for Health Sciences, Nijmegen, the Netherlands
| | - Joanne A de Hullu
- Department of Obstetrics and Gynaecology, Radboud University Medical Center, Radboud Institute of Health Sciences, Nijmegen, the Netherlands
| | - Johan Bulten
- Department of Pathology, Radboud University Medical Center, Nijmegen, the Netherlands
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