In a scenario of increasing incidence of cutaneous melanoma, it is only early detection that can prevent deaths because the survival rate depends on the tumor thickness at the time of detection. Patients, with cutaneous melanoma in situ (CMIS), have a 99% chance of survival and invasive cutaneous melanoma (ICM) patients have a 90% chance of survival if the vertical tumor thickness is less than 1mm at the time of detection. Therefore, the primary aim of melanoma detection should be tumor recognition and then surgery.

Dermatoscopy is an accurate, non-invasive diagnostic tool for evaluating pigmented skin lesions, especially CMIS and ICM. To establish the reliability of dermatoscopy structures as criteria for evaluating melanoma a study was conducted on 90 patients - 37 patients with CMIS and 53 patients with ICM.

Method

The CMIS patients were divided into three groups based on the greatest dimension of the lesion: less than or equal to 5mm, more than 5mm and equal to or less than 10mm and more than 10mm. The ICM patients were divided into two groups based on the vertical thickness of the tumor according to Breslow’s index: less than or equal to 0.75mm and greater than 0.75mm.

All lesions were covered with immersion oil to eliminate reflection from the skin surface. The lesions were examined with a dermatoscope and photographed at a magnification of 10. These photographs were then examined to find out the frequency of the classic dermatoscope criteria and to see if there existed any correlation between these criteria and dimensions of CMIS lesions and the vertical thickness of tumors in ICM.

The dermatoscope criteria that were used to evaluate the lesions were those believed to be associated with melanoma and included irregular pigment network, irregular extensions and branched streaks, gray-blue areas, extension pseudopods, brown globules, black dots, blue whitish veils, hypopigmentation, white scar-like areas, and linear and dotted vascular patterns. The diagnosis in most cases was based on classical pattern analysis.

Results

In CMIS lesions, the most frequently observed dermatoscope criteria were blue whitish veil, black dots and irregular extensions and branched streaks and were present in 78%, 76%, 73% and 62% of lesions respectively. Brown globules, irregular pigment network, pseudopods and hypopigmentation were present in 57%, 54%, 54% and 51% lesions respectively. None of the CMIS lesions showed up white scar-like areas and atypical vascular patterns, the two-dermatoscope criteria associated with ICM.

The frequency of pseudopods at 12% was the least in the CMIS group with the smallest lesion size. In the two groups with larger lesion sizes, the frequency was over 60%. The incidence of blue whitish gray had a similar distribution. Such differences in frequency between different groups were considered statistically significant. The frequency of irregular extensions and branched streaks increased and frequency of brown globules decreased, with reduced CMIS lesion size. Overall, no clinically significant differences were observed between the three CMIS groups.

In ICM lesions, the most frequently observed dermatoscopic criteria were blue whitish veil, black dots, irregular extensions and branched streaks and gray blue areas and these were present in 84%, 79%, 68% and 63% of lesions respectively. More data showed that dermatoscope criteria for ICM with a Breslow index of less than or equal to 0.75mm is similar to CMIS. There are no statistically significant differences between these two groups.

However, the frequency of irregular pigment network and pseudopods in ICM with a Breslow index of greater than 0.75mm differed significantly from CMIS and from the other ICM group. The differences between the two ICM groups were found statistically significant.

Conclusions

The dermatoscopic criteria for CMIS and ICM are basically the same although white scar-like areas and atypical vascular patterns were absent in CMIS lesions. The criteria generally seemed independent of CMIS lesion size. The exceptions were pseudopods and blue whitish veil, which were found more in smaller sized CMIS lesions.

A statistically significant difference was the presence of blue whitish veil in 100% ICM lesions compared to 79% in CMIS. This was considered important for the diagnosis of ICM as well as CMIS lesions. It should be noted that blue whitish veil indicates melanoma only in combination with pigment network.

Overall, the results show that dermatoscopy is a reliable method to diagnose CMIS and ICM. Because of similar dermatoscopic criteria, sometimes it may be difficult to differentiate CMIS from ICM. However, in both cases the dermatoscopy shows the need for excising the lesion. In any case the reliable classical pattern method can diagnose CMIS, independent of lesion dimensions.