Diagnostic utility of circumferential peripheral globules under dermoscopy in adults

Abstract

To the Editor: Circumferential peripheral globules (CPG) are an uncommon finding in the dermoscopic evaluation of melanocytic lesions and have been suggested to represent growth.1Bajaj S. Dusza S.W. Marchetti M.A. et al.Growth-curve modeling of nevi with a peripheral globular pattern.JAMA Dermatol. 2015; 151: 1338-1345Crossref PubMed Scopus (23) Google Scholar, 2Kittler H. Seltenheim M. Dawid M. Pehamberger H. Wolff K. Binder M. Frequency and characteristics of enlarging common melanocytic nevi.Arch Dermatol. 2000; 136: 316-320Crossref PubMed Scopus (141) Google Scholar, 3Rubegni P. Sbano P. Burroni M. et al.Melanocytic skin lesions and pregnancy: digital dermoscopy analysis.Skin Res Technol. 2007; 13: 143-147Crossref PubMed Scopus (35) Google Scholar They are mostly seen in childhood and are cited to seldomly occur after age 60 years.4Zalaudek I. Schmid K. Marghoob A.A. et al.Frequency of dermoscopic nevus subtypes by age and body site: a cross-sectional study.Arch Dermatol. 2011; 147: 663-670Crossref PubMed Scopus (90) Google Scholar Management of these lesions is mainly based on age. In younger individuals, lesions with CPG are often monitored. In older patients, however, biopsy is frequently performed.4Zalaudek I. Schmid K. Marghoob A.A. et al.Frequency of dermoscopic nevus subtypes by age and body site: a cross-sectional study.Arch Dermatol. 2011; 147: 663-670Crossref PubMed Scopus (90) Google Scholar The objective of this study was to describe the diagnostic accuracy and dermoscopic features of melanocytic lesions with CPG among adults and to identify candidate features to differentiate nevi from melanoma. The International Skin Imaging Collaboration database (www.isic-archive.com) was searched for dermoscopic images of melanocytic lesions with CPGs in November 2019. CPGs were defined as circular clods distributed around the lesion in at least 3 of 4 quadrants. Lesions in patients 20 years or younger and duplicate images were excluded. One author with expertise in dermoscopy was prompted to give a diagnosis for a lesion with 1) only the dermoscopic image and 2) the dermoscopic image plus context (patient age). Melanoma-specific structures were scored as present/absent by 3 dermatologists blinded to age and diagnosis. A structure was considered present if identified by 2 of the 3 reviewers. Of 20,748 images of melanocytic lesions, 238 (1.1%) met the inclusion criteria (Table I). After eliminating lesions in patients 20 years or younger, 99 (0.5%) images remained: 4 melanomas (4.0%) and 95 nevi (96.0%). The melanomas occurred in individuals aged 30, 35, 40, and 55 years. After dichotomizing by age 50 years, there was no difference in the proportion of melanomas (5.3% vs 3.9%; P >.99).Table IPresence of peripheral globules under dermoscopy by age groupAge group, yNevi, n (%)Melanoma, n (%)Total, n (%)Sensitivity (dermoscopy only), %Sensitivity (dermoscopy plus context), %Specificity (dermoscopy only), %Specificity (dermoscopy plus context), %(n = 234)(n = 4)(N = 238)<20139 (59.4)0 (0)139 (58.4)————20-2921 (9.0)0 (0)21 (8.8)10066.784.980.830-3933 (14.1)2 (50)35 (14.7)40-4919 (8.1)1 (25)20 (8.4)50-596 (2.6)1 (25)7 (2.9)089.510015.860-699 (3.8)0 (0)9 (3.8)70-792 (0.9)0 (0)2 (0.8)80-892 (0.9)0 (0)2 (0.8)Unknown3 (1.3)0 (0)3 (1.3)———— Open table in a new tab The overall sensitivity and specificity of diagnosing melanoma given only a dermoscopic image were 75% and 86.3%, respectively. After the addition of context (i.e. age), the sensitivity remained at 75%, but the specificity decreased to 67.4%. All melanomas and 76.8% of nevi had at least 1 melanoma-specific structure. Structures more prevalent among melanomas included off-center blotches (odds ratio, 88.0; 95% confidence interval, 6.95-1114.65; P = .0005) and peripheral tan structureless areas (odds ratio, 14.83; 95% confidence interval, 1.04-212.48; P = .047) (Fig 1). The diagnostic utility of CPG in differentiating nevi from melanoma in adults is unclear. Unlike Zalaudek et al,4Zalaudek I. Schmid K. Marghoob A.A. et al.Frequency of dermoscopic nevus subtypes by age and body site: a cross-sectional study.Arch Dermatol. 2011; 147: 663-670Crossref PubMed Scopus (90) Google Scholar who did not identify peripheral globules in patients 60 years and older, we found 6% to be in this group, none of which were melanomas. Although close observation or excision has been recommended in patients 50 years and older,4Zalaudek I. Schmid K. Marghoob A.A. et al.Frequency of dermoscopic nevus subtypes by age and body site: a cross-sectional study.Arch Dermatol. 2011; 147: 663-670Crossref PubMed Scopus (90) Google Scholar this age cutoff was not associated with melanoma in our study. Furthermore, when clinical context was added, the reader actually decreased specificity without changing sensitivity. Lesions with peripheral globules exhibiting any melanoma-specific structure should be excised, independent of age. Based on our data, the presence of off-centered blotches with tan structureless areas in a lesion with peripheral globules may be a useful diagnostic clue for melanoma. In addition, evaluation of the organization and symmetry of structures and colors provides valuable information. Limitations of our study include its retrospective type and the inclusion bias of preselected lesions for imaging. Overall, these results highlight the need for larger studies to reassess the management of melanocytic lesions with peripheral globules in older patients.