Nodular Melanoma

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 Authored by: Ralph P. Braun     ·  Scott Menzies

 Keywords:   melanoma · nodular · nodular melanoma
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Description This chapter reviews the dermoscopyDermoscopy is a non invasive diagnostic method. criteriaThis glossary term has not yet been described. of nodular melanomaThis glossary term has not yet been described.
Author(s) Ralph P. Braun · Scott Menzies
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Status update June 14, 2017
Status by Ralph P. Braun
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Nodular melanomas (NMs) are defined as invasive melanomas without a radial growth phase. Specifically, they lack an in situThis glossary term has not yet been described. component beyond three rete ridges of the invasive vertical growth phase. While they represent only 14% of invasive melanomas, whereas they represent the majority of thick melanomas (>3 mm Breslow thickness).

Clinically, NMs may lack the “ABCD” features more typical of superficialThis glossary term has not yet been described. spreadingThis glossary term has not yet been described. melanomas (SSMs) since they appear as a symmetric lesion.

The classic melanomaThis glossary term has not yet been described. specific criteria are predominantly seen in SSMs but much less frequently in NMs.

Especially the features correlating with the radial growth of melanoma and pagetoid spread (pseudopodsBulbous and often kinked projections seen at the lesion edge, either directly associated with a network or solid tumor border., radial streamingRadial linear extensions at the lesion edge) as well as those criteria found in thin melanoma (such as atypical broadened network and the early regressionThis glossary term has not yet been described. feature of multiple blue-gray fine dots or peppering) are often lacking in NMs.

However, pigmented NMs more frequently have those dermoscopy features associated with thick melanoma[1] :

  • blue-white veil
  • multiple (5–6) colors
  • crystalline structures (seen only with polarized lightThis glossary term has not yet been described.)
  • atypical vascular patterns

In a more recent publication using multivariate analysis the following criteria were found to be highly significant for nodular melanoma[2]

  • asymmetric pigmentation
  • blue–black pigmented areas
  • homogeneous disorganized pattern
  • combination of polymorphous vesselsmultiple types of vessels are present may indicate malignancy in appropriate context for example in flat melanocytic lesions and milky-red globulesThis glossary term has not yet been described./areas
  • combination of polymorphous vessels and red homogeneous areas

Nodular melanoma schematic.jpg

Melanomas tend to have an asymmetric pigmentation pattern under dermoscopy. While most NM are asymmetric, 6% have a symmetric pattern [1] . Nevertheless, the majority of pigmented NMs can be diagnosed using standard dermoscopy criteria.

What is diagnostically problematic is the fact that a significant number (more than a third) of NMs are hypomelanotic or amelanotic. In these cases, atypical vascular patterns may be the only cluesThis glossary term has not yet been described. for the diagnosisThis glossary term has not yet been described. of such lesions [1]. The most significant of these patterns are the combination of linear irregularlinear vessels with multiple bends and dotted vesselstiny pinpoint vessels flat melanocytic lesions inflammatory diseases Bowen disease or linear irregular vesselsThis glossary term has not yet been described. as the predominant vessel type, greater than one shade of pink, milky red-pink areas and or globules, and hairpin vessels.



Nodular melanoma schematic 2.jpg


References:
  1. 1.0 1.1 1.2 Menzies et al.: Dermoscopic evaluation of nodular melanoma. JAMA Dermatol 2013;149:699-709. PMID: 23553375. DOI.
  2. Pizzichetta et al.: Pigmented nodular melanoma: the predictive value of dermoscopic features using multivariate analysis. Br. J. Dermatol. 2015;173:106-14. PMID: 25916655. DOI.