Correlation Between Acanthosis Nigricans Scoring Chart (ANSC) and Narrowband Reflectance Spectrophotometer in Assessing Severity of Acanthosis Nigricans

Introduction: There is a lack of standardized tool to monitor treatment outcome of acanthosis nigricans. To meet this end, we developed the Acanthosis Nigricans Scoring Chart (ANSC) that evaluates skin color (score range of 1-8) and skin texture (score range of 1-6), which adds up to a total ANSC score (score range of 2-14). We aimed to determine the correlation of ANSC to narrowband reflectance spectrophotometry and to evaluate its reliability.

Methods: A cross-sectional study was conducted in adult acanthosis nigricans patients. Two raters independently graded participants using ANSC twice, in which scores were correlated to readings from Mexameter MX18. Intra- and interrater reliability were also evaluated via intraclass correlation coefficient (ICC).

Results: Participants had mean (sd) melanin and erythema indices of 615.8 (176.2) and 451.4 (53.4), respectively. Mean (sd) total ANSC score was 9.43 (2.43). The total ANSC score and skin color subdomain demonstrated strong correlations (r > 0.6) with spectrophotometric results, whereas skin texture showed a moderate correlation (r = 0.4-0.6). Total ANSC score generally had excellent intra- and interrater reliabilities (ICC > 0.85).

Conclusion: The total ANSC score and its subdomains strongly correlate with spectrophotometer and demonstrate excellent reliability in assessing acanthosis nigricans.