J Cutan Pathol 2015: 42: 953 – 958 doi: 10.1111/cup. 12589 John Wiley & Sons. Printed in Singapore © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Journal of Cutaneous Pathology Prior knowledge of the clinical picture does not introduce bias in the histopathologic diagnosis of melanocytic skin lesions A common debate among dermatopathologists is that prior knowledge of the clinical picture of melanocytic skin neoplasms may introduce a potential bias in the histopathologic examination. Histologic slides from 99 melanocytic skin neoplasms were circulated among 10 clinical dermatologists, all of them formally trained and board-certiied dermatopathologists: 5 dermatopathologists had clinical images available after a ‘blind’ examination (Group 1); the other 5 had clinical images available before microscopic examination (Group 2). Data from the two groups were compared regarding ‘consensus’ (a diagnosis in agreement by ≥4 dermatopathologists/group), chance-corrected interobserver agreement (Fleiss’ k ) and level of diagnostic conidence (LDC: a 1–5 arbitrary scale indicating ‘increasing reliability’ of any given diagnosis). Compared with Group 1 dermatopathologists, Group 2 achieved a lower number of consensus (84 vs. 90) but a higher k value (0.74 vs. 0.69) and a greater mean LDC value (4.57 vs. 4.32). The same consensus was achieved by the two groups in 81/99 cases. Spitzoid neoplasms were most frequently controversial for both groups. The histopathologic interpretation of melanocytic neoplasms seems to be not biased by the knowledge of the clinical picture before histopathologic examination. Keywords: clinical information, clinicopathologic correlation, dermoscopy, histopathologic diagnosis, melanocytic skin neoplasms Ferrara G, Annessi G, Argenyi Z, Argenziano G, Beltraminelli H, Cerio R, Cerroni L, Cota C, Simonetti S, Stefanato CM, Zalaudek I, Kittler H, Soyer HP. Prior knowledge of the clinical picture does not introduce bias in the histopathologic diagnosis of melanocytic skin lesions. J Cutan Pathol 2015; 42: 953 – 958. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Gerardo Ferrara 1 , Giorgio Annessi 2 , Zsolt Argenyi 3 , Giuseppe Argenziano 4 , Helmut Beltraminelli 5 , Rino Cerio 6 , Lorenzo Cerroni 7 , Carlo Cota 8 , Stefano Simonetti 9 , Catherine M. Stefanato 10 , Iris Zalaudek 11 , Harald Kittler 12 and H. Peter Soyer 13 1 Anatomic Pathology Unit, Gaetano Rummo General Hospital, Benevento, Italy, 2 Dermatopathology Unit, Istituto Dermopatico dell’Immacolata, Rome, Italy, 3 Department of Dermatology, University of Washington, Seattle, Seattle, WA, USA, 4 Department of Dermatology, Second University of Naples, Naples, Italy, 5 Department of Dermatology, Inselspital – Bern University Hospital, Bern, Switzerland, 6 Department of Dermatology, University of London, London, UK, 7 Research Unit Dermatopathology, Department of Dermatology, Medical University of Graz, Graz, Austria, 8 Dermatopathology Unit, San Galligano Dermatological Institute, Rome, Italy, 9 Department of Dermatology, Ospedale Santa Maria della Misericordia, Perugia, Italy, 10 Department of Dermatopathology, St John’s Institute of Dermatology, St Thomas’ Hospital, London, UK, 11 Department of Dermatology, Medical University of Graz, Graz, Austria, 12 Department of Dermatology, Division of General Dermatology, Medical University of Vienna, Vienna, Austria, and 13 Dermatology Research Centre, The University of Queensland, School of Medicine, Translational Research Institute, Brisbane, Australia Gerardo Ferrara Department of Oncology, Anatomic Pathology Unit, ‘Gaetano Rummo’ General Hospital, Via dell’Angelo 1, I82100 Benevento, Italy Tel: +390 82457315 Fax: +390 82457334 e-mail: gerardo.ferrara@libero.it Accepted for publication April 27, 2013 953