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614 SHORT COMMUNICATION Nevus Count Associations with Thinner Nodular or Superficial Spreading Melanoma Clio DESSINIOTI 1 , Alan C. GELLER 2 , Arabella STERGIOPOULOU 1 , Susan M. SWETTER 3 , Eszter BALTAS 4 , Jonathan E. MAYER 5 , Timothy M. JOHNSON 6 and Alexander J. STRATIGOS 1 1 st 1 Department of Dermatology-Venereology, National and Kapodistrian University of Athens School of Medicine, Andreas Sygros Hospital, 5 I. Dragoumi Str, GR-16121 Athens, Greece, 2 Department of Social and Behavioral Sciences, Harvard TH Chan School of Public Health, Boston, MA, 3 Department of Dermatology, Pigmented Lesion and Melanoma Program, Stanford University Medical Center and VA Palo Alto Health Care System, Palo Alto, CA, USA, 4 Department of Dermatology and Allergology, University of Szeged, Szeged, Hungary, 5 Department of Dermatology, University of Colorado School of Medicine, Aurora, CO, USA, and 6 Department of Dermatology, University of Michigan, USA. E-mail: [email protected] Accepted Feb 7, 2019; E-published Feb 8, 2019 Cutaneous melanoma (CM) accounts for 90% of deaths from skin cancer and models suggest continuous increases in melanoma incidence through 2031 (1). Breslow thickness is an important adverse staging and prognostic factor; however, the nodular (NM) histologic subtype was independently associated with higher mor- tality risk among thin (≤ 1 mm) melanomas (2). Further distinct characteristics associated with NM compared to SSM even among thinner tumors include a higher mitotic rate (3), and the difficulty to detect thinner melanoma by skin self-examination (4). Total-body melanocytic nevus counts and dysplastic nevi are important established phenotypic markers of me- lanoma risk, representing surrogate markers of underly- ing genetic factors and environmental sun exposure. The recognition of nevus count associations with melanoma subtypes, and particularly with NM, may contribute to the understanding of the biology as well as the earlier detection of this aggressive melanoma subtype. This multicenter study aimed to examine the association of concomitant melanocytic nevi counts in patients with melanoma of the nodular type compared to the superficial spreading melanoma (SSM) histological type, and how this may differ by Breslow thickness. METHODS Pooled data were collected from 3 cross-sectional surveys among 4 dermatology-based melanoma referral centers at Stanford Uni- versity and University of Michigan in the US, at the University of Athens and collaborating centers in Greece, and at the University of Szeged in Hungary. Consecutive, newly-diagnosed patients aged ≥ 18 years, with primary invasive melanoma of the NM and SSM subtype, were included. The same structured questionnaire was used, based on the study by Swetter et al. (5). Accepted criteria for histopathologic clas- sification of SSM vs NM subtype were employed (6). The number of common melanocytic nevi ≥ 2 mm in diameter and clinically atypical nevi (CAN) on the whole body, was recorded by clinical examination by a dermatologist. The number of common nevi was recorded as either of 3 categories: zero or < 20, 20–50 nevi or > 50 nevi. A clinically atypical nevus was defined as a nevus ≥ 5 mm in diameter, with variable pigmentation and an irregular or diffuse edge. Institutional review board/ethics approval and informed patient consent was obtained at all sites. For the statistical analysis, for thinner melanoma, the use of a ≤ 2 mm cut-off was used since only 4 NMs in the entire data set were diagnosed with thickness ≤ 1 mm, which precluded any reliable doi: 10.2340/00015555-3142 Acta Derm Venereol 2019; 99: 614–615 analysis. To investigate the association of thinner melanoma with every nevus variable (number of common nevi, presence of CAN, number of CAN), multiple logistic regression analysis was carried out including statistically significant variables from the univariate analysis. Each nevus variable was investigated in a separate logistic model. Stratified analyses for nevi were conducted by stratifying the data into patients aged < 50 and ≥ 50 years, since nevi involute with age. All p-values were two-sided and the significance level was < 0.05. Analyses were carried out using STATA, version 13 (StataCorp. 2013. Stata Statistical Software: Release 13. College Station, TX: StataCorp LP). RESULTS Of 713 patients, 158 had NM and 555 had SSM. Patient and melanoma characteristics by NM or SSM histologi- cal type are presented in Table SI 1 . NM were significantly thicker compared to SSM (median Breslow: 2.94 mm vs 0.85 mm respectively, p < 0.001). Overall, there was no association of the NM or SSM type with common nevi counts (p = 0.826), the presence of clinically atypical nevi (p = 0.289), or the number of atypical nevi (p = 0.529). Among the 158 patients with NM, 50 (32%) had at least one CAN. Total nevi counts were not associated with the location of melanoma on the head/neck, trunk or extremities (data not shown). In multivariate logistic analysis adjusted for age, sex, thickness and country, there was no association of NM compared to SSM (reference) with nevi counts (odds ratio [OR] (confidence interval) [CI] 0.93 (0.55–1.58)) or with the number of atypical nevi (OR (95% CI) 0.81 (0.46–1.45)). Similarly, there were no nevi associations in the multivariate analysis for thicker NM (> 2 mm) compared to thinner NM (≤ 2 mm), or for thicker SSM compared to thinner SSM (data not shown). Lower nevus counts were more frequent in older patients. Patients with NM ≥ 50 years old compared to younger patients more frequently had lower (< 20) nevus counts (p = 0.003), and less frequently had any CAN present (p < 0.001). Similar findings were found for SSM (data not shown). Age-stratified multivariate logistic regression analysis showed that for patients ≥ 50 years old, the presence of fewer nevi (0–20) com- https://www.medicaljournals.se/acta/content/abstract/10.2340/00015555-3142 1 This is an open access article under the CC BY-NC license. www.medicaljournals.se/acta Journal Compilation © 2019 Acta Dermato-Venereologica.