• Matthew J Lin, Charles Xie, Yan Pan, Chris Jalilian, and John W Kelly.
• Victorian Melanoma Service, Alfred Hospital, Melbourne, Victoria, Australia.
• Australas. J. Dermatol. 2019 Feb 1; 60 (1): 45-49.

Background/ObjectivesAmelanotic nodular melanomas are notoriously difficult to diagnose and are responsible for a disproportionate burden of melanoma mortality. It is important to distinguish them from other amelanotic nodules. This study aimed to describe the dermoscopic features of a series of nodular melanomas and other amelanotic nodules and to determine whether dermoscopy improves diagnostic accuracy.MethodRetrospective analysis of 150 clinically amelanotic nodules with macroscopic and dermoscopic images.ResultsIn terms of classifying the nodules as malignant, dermoscopy was superior to unaided eye (specificity 89%; 95% CI 71-98% vs 67%; 95% CI 46-83%, P = 0.03). Dermoscopy enhanced sensitivity for the diagnosis of both amelanotic melanoma and SCC. In 19% of cases, using dermoscopy, the most likely diagnosis was changed from incorrect to correct. This included 26% of amelanotic melanomas which had a macroscopic misdiagnosis overturned to the correct diagnosis. Polymorphous vascular structures were more common in malignant nodules. 76% of amelanotic melanomas/Merkel cell carcinomas had polymorphous vessels compared with 38% of SCCs/KAs/BCCs and 22% of benign nodules (P < 0.001).ConclusionDermoscopy improves diagnostic accuracy for amelanotic melanomas and other amelanotic nodules. Although dermoscopy improves diagnostic accuracy for amelanotic melanomas, these aggressive melanomas remain diagnostically difficult.© 2018 The Australasian College of Dermatologists.

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