ANALYZING THE SPATIAL RANDOMNESS IN THE DISTRIBUTION OF ACQUIRED MELANOCYTIC NEOPLASMS.

Overview

Based on the clinical impression and current knowledge, acquired melanocytic nevi and melanomas may not occur in random localizations. The goal of this study was to identify whether their distribution on the back is random and the location of melanoma correlates with its adjacent lesions. Therefore, patient-level and lesion-level spatial analyses were performed using the Clark-Evans test for complete spatial randomness (CSR). 311 patients with 3D total body photography (average age 40.08 [30-49]; male/female ratio: 128/183) with 5108 eligible lesions in total were included in the study (mean sum of eligible lesions per patient 16.42 [3-199]). The patient-level analysis revealed that the distributions of acquired melanocytic neoplasms were more likely to deviate towards clustering than dispersion (average z-score -0.55 [95% CI -0.69 to -0.41; P<.001]). The lesion-level analysis indicated a higher portion of melanomas (79.2% [n=57/72, 95% CI 69.4% to 88.9%]) appearing in proximity to neighboring melanocytic neoplasms compared to nevi (45.3% [n=2281/5036, 95% CI 43.9% to 46.7%]). In conclusion, the nevi and melanomas' distribution on the back tends towards clustering as opposed to dispersion. Furthermore, melanomas are more likely to appear proximally to their neighboring neoplasms than nevi. These findings may justify various oncogenic theories and improve diagnostic methodology.