Martin G Cook1,2,3,4, Daniela Massi4,5, Willeke A M Blokx4,6, Joost Van den Oord4,7, Senada Koljenović4,8, Vincenzo De Giorgi9, Eleanor Kissin10, Megan Grant2, Amit Mandal2, Gabriela Gremel2, Caroline Gaudy2, Amaya Viros2, Nathalie Dhomen2, Kiarash Khosrotehrani11,12, Richard Marais2, Adele C Green2,13, Martin C Mihm4,14. 1. Histopathology, Royal Surrey County Hospital, Guildford, UK. 2. Molecular Oncology Group, CRUK Manchester Institute, University of Manchester, Manchester, UK. 3. Division of Clinical Medicine, University of Surrey, Guildford, Surrey, UK. 4. Members of EORTC Melanoma Group Pathology Working Group, Florence, Italy. 5. Division of Pathological Anatomy, Department of Surgery and Translational Medicine, University of Florence, Florence, Italy. 6. Department of Pathology, Radboud University Medical Centre, Nijmegen, the Netherlands. 7. Translational Cell and Tissue Research, Department of Imaging and Pathology, University of Leuven (KU Leuven), Leuven, Belgium. 8. Department of Pathology, Erasmus University Medical Centre, Rotterdam, the Netherlands. 9. Department of Dermatology, University of Florence, Florence, Italy. 10. Eleanor Kissin, Department of Plastic Surgery, St George's Hospital, London, UK. 11. Department of Dermatology, Princess Alexandra Hospital, Brisbane, Queensland, Australia. 12. The University of Queensland, UQ Diamantina Institute, Translational Research Institute, Brisbane, Queensland, Australia. 13. QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia. 14. Brigham and Women's Hospital, Boston, MA, USA.
Abstract
AIMS: Because the term 'naevoid melanoma' has variable clinical and pathological interpretations, we aimed to clarify the features of melanomas referred to as naevoid. METHODS AND RESULTS: A review was undertaken of 102 melanomas diagnosed histopathologically as naevoid melanomas and ascertained by European Organization for Research and Treatment of Cancer Melanoma Group Subcommittee pathologists from their records. We found these could be classified morphologically into three groups. Thirteen melanomas were overlying genuine naevi and were therefore excluded. Of the 89 melanomas considered to be naevoid, 11 presented clinically as exophytic papillomatous nodules with little junctional component and composed of small atypical cells showing numerous mitoses and no change with depth; we termed these 'papillomatous naevoid' melanomas. The other 78 were flat or only slightly raised, and had a superficial spreading melanoma-like component with maturation to a small cell, but still an atypical, dermal component; we termed these 'maturing naevoid' melanomas. We showed that papillomatous and maturing naevoid melanomas also have differing immunochemical profiles. Preliminary clinical follow-up suggested different outcomes for these two naevoid melanoma types. CONCLUSIONS: Melanomas that have been classified as naevoid melanomas comprise two types with distinct clinical, histopathological and immunohistochemical features that may also be prognostically significant.
AIMS: Because the term 'naevoid melanoma' has variable clinical and pathological interpretations, we aimed to clarify the features of melanomas referred to as naevoid. METHODS AND RESULTS: A review was undertaken of 102 melanomas diagnosed histopathologically as naevoid melanomas and ascertained by European Organization for Research and Treatment of Cancer Melanoma Group Subcommittee pathologists from their records. We found these could be classified morphologically into three groups. Thirteen melanomas were overlying genuine naevi and were therefore excluded. Of the 89 melanomas considered to be naevoid, 11 presented clinically as exophytic papillomatous nodules with little junctional component and composed of small atypical cells showing numerous mitoses and no change with depth; we termed these 'papillomatous naevoid' melanomas. The other 78 were flat or only slightly raised, and had a superficial spreading melanoma-like component with maturation to a small cell, but still an atypical, dermal component; we termed these 'maturing naevoid' melanomas. We showed that papillomatous and maturing naevoid melanomas also have differing immunochemical profiles. Preliminary clinical follow-up suggested different outcomes for these two naevoid melanoma types. CONCLUSIONS: Melanomas that have been classified as naevoid melanomas comprise two types with distinct clinical, histopathological and immunohistochemical features that may also be prognostically significant.