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March 2003

Nodular Melanoma Is Not a Distinct Entity

Author Affiliations

Copyright 2003 American Medical Association. All Rights Reserved. Applicable FARS/DFARS Restrictions Apply to Government Use.2003

Arch Dermatol. 2003;139(3):387-388. doi:10.1001/archderm.139.3.387-a

Chamberlain et al1 assert that they and others2 have identified early nodular melanoma (NM), ie, less than 1 mm thick and Clark level II. The reference cited was a letter by Bergenmar et al,2 written in response to a letter that questioned the validity of the concept of NM as a distinct entity.3 Bergenmar et al,2 however, appeared to have confused the definition of NM with that of vertical growth phase, which can occur in any type of melanoma. Their letter, therefore, offered no evidence to support the claim that they were diagnosing NM in level II. In an analysis of 201 cases of NM in Western Australia, none was diagnosed in the stage of level II invasion, supporting the view that NMs differ from the other common forms of melanoma only in their advanced stage of development at the time of diagnosis.4 This concept appears to be supported by the finding of Chamberlain et al1 that the only consistent difference between NM and superficial spreading melanoma was thickness, indicating that the development of a nodule in a melanoma should be recognized as a gross manifestation of the development of metastatic potential, not as a distinct type of melanoma.4,5