Clinical, Dermoscopic and Reflectance Confocal Microscopy Characteristics Associated With the Presence of Negative Pigment Network Among Spitzoid Neoplasms

Negative pigment network (NPN) is a dermoscopic structure frequently associated with melanoma. Though commonly observed in Spitz naevi (SN) and Spitzoid melanoma (SM), its reflectance confocal microscopy (RCM) correlates have been primarily studied in non-Spitzoid melanocytic neoplasms. This study aimed to identify clinical, dermoscopic, and RCM features associated with dermoscopic NPN in Spitzoid neoplasms and explore its histopathological correlates. We retrospectively analysed clinical, dermoscopic, and RCM images from 128 histopathologically confirmed SN and SM cases diagnosed between 2014 and 2020. Lesions were grouped by presence or absence of dermoscopic NPN, and comparisons were made across clinical, dermoscopic, and RCM features. A subset of 20 cases underwent histopathologic correlation. Of the 128 cases, 96 (74%) were SN and 32 (26%) SM. NPN was present in 58 lesions (45%)—40 SN (42%) and 18 SM (56%). NPN was associated with lesion diameter ≥ 5 mm, presence of shiny white structures, dotted vessels, and inversely associated with diffuse blue-white veil. SMs showed higher frequencies of asymmetry, multicomponent patterns, and extensive NPN. RCM features previously linked to NPN—round or linear surface disruptions, bright suprabasal areas, and broadened interpapillary spaces—were seen in 87% of cases but did not correlate with diagnosis or dermoscopic NPN. Corresponding histologic features included keratin-filled dells, hypergranulosis, and broadened rete ridges or infundibula. RCM correlates of dermoscopic NPN are frequently observed in Spitzoid neoplasms, independent of visible dermoscopic NPN, suggesting perceptibility may depend on contrast within dermoscopic patterns.