“White” network in Spitz nevi and early melanomas lacking significant pigmentation

Abstract

Spitz nevi and early melanomas lacking significant pigmentation exhibit overlapping dermoscopic patterns of regularly arranged dotted vessels over a pink background. Although white network has been described in both tumors, little is known about the frequency of this pattern in both tumors. We sought to compare the frequency of white network in Spitz nevi and early melanomas lacking significant pigmentation and to correlate this feature with histopathology. Two independent dermoscopists scored the presence of white network in a series of retrospectively collected images of histopathologically diagnosed cases of Spitz nevi and melanomas, dermoscopically typified by dotted vessels. A total of 65 cases including 39 melanomas (median thickness 0.4 mm) and 26 Spitz nevi were analyzed. Patients with Spitz nevi were significantly younger compared to patients with melanoma (mean age: 26.8 vs 51.2 years, respectively; P < .001). The 2 observers scored white network being present in 23 (88.5%) and 24 (92.3%) Spitz nevi compared with 10 (25.6%) and 8 (20.5%) cases of 39 melanomas, respectively (P < .001). Interobserver agreement for white network was good (kappa= 0.67; 95% confidence interval 0.44-0.90). Histopathologically, elongated rete ridges were observed in 22 (88.5%) Spitz nevi and 11 (36.7%) melanomas (P < .001). We did not evaluate other dermoscopic-histopathologic correlates commonly seen in Spitz nevi and melanomas in our study. Although white network occurs at significantly higher frequency among hypopigmented/amelanotic Spitz nevi compared with early melanoma, it is not exclusively seen in Spitz nevi. Thus,excision of melanocytic tumors showing this pattern is mandatory.