A retrospective cohort study of the diagnostic value of different subtypes of atypical pigment network on dermoscopy

Background: Atypical network encompasses several patterns. Few studies assess the sensitivity, specificity, and positive and negative predictive values of network subtypes. Objective: We assessed the diagnostic value of atypical network subtypes and their histopathologic correlates in cutaneous melanocytic lesions. Methods: A retrospective search (2014-2018) from a high-risk melanoma clinic for cases scored for atypical network with accompanying dermoscopic photographs yielded 120 lesions (15 melanoma; 30 severely, 38 moderately, and 32 mildly atypical nevi; 4 compound nevi; and 1 junctional nevus). A dermatopathologist blinded to diagnosis assessed dermoscopic and histologic features. Network abnormality correlates with histopathology and clinical diagnoses were assessed with sensitivity, specificity, positive and negative predictive values, and odds ratios. Results: A multivariable model with shiny white streaks (odds ratio 3.02) and inverse network (OR 4.46) was most predictive of melanoma or severe atypia. Positive predictive value for melanoma or severe atypia in decreasing order was inverse network (73.9%), shiny white streaks (71.4%), loss of network (46%), branched streaks (29.4%), and thick brown lines (28.4%). Limitations: Cases were retrospectively found from a pigmented lesion clinic and evaluated by a single dermatopathologist. Conclusion: Shiny white streaks and inverse network are most predictive of melanoma or severe atypia and warrant biopsy if found on dermoscopy.