The measurement of melanoma thickness according to Breslow is an accurate, reproducible and objective predictor of prognosis [Breslow 1975]. It is used to establish the size of the surgical margin, as well as to select patients for sentinel lymph node biopsy [Balch 1993, Brady 1997, Ho 1990, NIH Consensus Conference 1992, Veronesi 1988]. Therefore, it would be useful to have preoperative parameters supplying reliable information on tumor thickness to ensure a correct surgical approach.

Clinical criteria have been used to determine melanoma thickness, although the reliability of melanoma palpability in predicting its actual histopathologic thickness has not been confirmed by subsequent studies [Neades 1993, O’Donnell 1996, Taylor 1985].

Dermoscopic criteria for the in vivo detection of the various phases of melanoma progression as well as tumor depth have been recently described [Argenziano 1997]. In particular, a significant association was found between pigment network, blue-whitish veil, and vascular pattern on one side and melanoma thickness on the other. This evidence was supported by the following considerations:

  1. Pigment network (PN) is an expression of the epidermal architecture and its occurrence inversely correlates with melanoma thickness, presumably because of a loss of rete ridges which may occur with the progression of the neoplasia [Soyer 1989, Stolz (Blackwell Science) 1994].

  2. Blue-whitish veil (BWV) corresponds to an acanthotic epidermis with focal hypergranulosis above sheets of heavily pigmented melanocytes in the dermis [Yadav 1993]. Dermoscopically this feature appears as a confluent, gray-blue to whitish-blue diffuse pigmentation associated with pigment network alterations, dots/globules and/or streaks. It must be differentiated from blue areas (gray-blue areas, peppering, multiple blue-gray dots) that are commonly associated with white areas and histopathologically correlate with fibrosis and variable amounts of melanophages. By using this definition a blue-whitish veil is observed in 78% of melanomas >0.75 mm thick and only in 21% of melanomas <0.76 mm thick.

  3. A vascular pattern is observed in regressive melanomas but also commonly in hypopigmented melanomas or in melanomas with pronounced hypopigmented areas. Atypical vascular patterns (AVP) are defined as vascular structures irregularly distributed throughout a given melanoma but not associated with regression structures: 

  1. linear irregular vessels; presumably the expression of melanoma neovascularization;

  2. dotted regular vessels; perpendicular to the skin surface [Kreusch 1991]. 

Under this definition, AVPs are seen in 66% of melanomas >0.75 mm thick and only in 14% of melanomas <0.76 mm thick.

Combinations of clinical and dermoscopic criteria have subsequently been proven to increase accuracy in the preoperative evaluation of melanoma thickness with respect to clinical elevation, assessed as flat, palpable, or nodular, and in the context of the above mentioned dermoscopic criteria [Argenziano 1999].



According to the degree of clinical elevation, a given lesion is categorized as flat, palpable, or nodular. In addition, the largest diameter and the presence of pigment network, blue-whitish veil, and atypical vascular pattern are also evaluated. 

This algorithm is based on the combined use of clinical and dermoscopic criteria and gives the likelihood of a given melanoma belonging to one of the three groups of tumor thickness: 

  1. Thin melanoma with thickness <0.76 mm (including in situ melanomas);

  2. Intermediate melanoma with thickness between 0.76 and 1.5 mm;

  3. Thick melanoma with >1.5 mm thickness.

a. Criteria most predictive for thin melanoma

  • flat lesion (100% likelihood)

  • palpable lesion with no blue-whitish veil or atypical vascular pattern (81% likelihood)

  • palpable lesion with pigment network and either blue-whitish veil or atypical vascular pattern (73% likelihood)

  • nodular lesion with no blue-whitish veil or atypical vascular pattern (in rare cases of thin melanoma arising in association with preexisting melanocytic nevus)

b. Criteria most predictive for intermediate-thickness melanoma

  • palpable lesion with both blue-whitish veil and atypical vascular pattern (82% likelihood)

c. Criteria most predictive for thick melanoma

  • nodular lesion of a diameter >15 mm with blue-whitish veil and/or atypical vascular pattern (70% likelihood)

d. Criteria most predictive for melanoma >0.75 mm thick

  • palpable lesion with blue-whitish veil and atypical vascular pattern (82% likelihood)

  • nodular lesion with blue-whitish veil and/or atypical vascular pattern (97% likelihood)

By subdividing all melanomas into two groups of less than, or greater than, 0.75 mm thickness, these 
combinations allow correct thickness predictions in 93% of TnM and 82% of melanomas >0.75 mm, for 
a total of 89% of cases [Argenziano 1999].



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