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Minagawa A, Koga H, Uhara H, Yokokawa Y, Okuyama R. Age-Related Prevalence of Dermoscopic Patterns in Acquired Melanocytic Nevus on Acral Volar Skin. JAMA Dermatol. 2013;149(8):989–990. doi:10.1001/jamadermatol.2013.4452
A new classification system was proposed based on the age-related dermoscopic global patterns of melanocytic nevus,1 ie, a globular pattern predominating in childhood in contrast to a reticular pattern that occurs increasingly with older age.2 However, these investigations were mainly performed on nonvolar skin. Herein, we investigated the prevalence of dermoscopic patterns in acral acquired melanocytic nevus (AMN) by age.
This study was approved by the institutional review board of Shinshu University School of Medicine. We retrospectively examined dermoscopic images of AMN located on acral volar skin in patients who visited our clinic between June 2000 and December 2010 (see eMethods in Supplement). These data included previously reported 56 lesions of AMN.3 We collected lesions presenting at least 4 months after birth to exclude lesions that we previously reported as congenital melanocytic nevus (CMN).4
Cases were divided into 4 groups according to age at the time of first visit: younger than 20 years, 20 to 39 years, 40 to 59 years, and older than 59 years. Each dermoscopic image was classified into the following: parallel furrow, latticelike, fibrillar, parallel ridge, homogeneous, globular, reticular, transition, globulostreaklike, crista dotted, and “peas-in-a-pod” patterns. Correlation between frequencies of dermoscopic pattern and age group was statistically analyzed (see eMethods in Supplement).
A total of 420 lesions in 365 Japanese patients were included. Mean and median ages of the patients were 32.0 and 31.0 years, respectively (range, 1-83 years), and the female to male ratio was 252:113. Mean and median lesion sizes were 5.7 and 5.1 mm (range, 1-28 mm), and the palmoplantar ratio was 50:370.
The lesion numbers are shown per dermoscopic pattern and age group in the Table. All 4 lesions presenting parallel ridge pattern were histopathologically confirmed to be benign. Frequencies of dermoscopic pattern of acral AMN per age group are summarized in the Figure. The frequencies of fibrillar and peas-in-a-pod patterns decreased with age, while the nontypical pattern increased. There was a significant correlation between the frequency of dermoscopic pattern and age group (P = .002 for all). Furthermore, the peas-in-a-pod and fibrillar patterns were significantly prevalent in the younger-than-20-years group (P < .001) and the 20-to-39-years group (P = .046), respectively, and less prevalent in the older-than-59-years group (P = .046 and P = .03, respectively). Meanwhile, the nontypical pattern was significantly prevalent in the older-than-59-years group (P < .001) and less prevalent in the younger-than-20-years group (P = .005). There were no significant differences in the frequencies of parallel furrow and latticelike patterns between age groups. Parallel ridge, reticular, globular, and homogeneous patterns were regarded as unsuitable for statistical analysis because of the small sample size.
This study revealed that the peas-in-a-pod and fibrillar patterns were common in younger patients, whereas the nontypical pattern was prevalent in older patients. The peas-in-a-pod pattern, previously reported as a characteristic pattern for small CMN,4 was also observed among AMN, with a significant prevalence in younger generation. The peas-in-a-pod pattern could be characteristic in volar skin during childhood, similar to the globular pattern in trunk and extremities.5 In the peas-in-a-pod pattern, dots on the ridges were histopathologically correlated with eliminated nevus cell nests in some cases.3 Further histopathological examination is essential to reveal the mechanism of age-related dermoscopic pattern as well as age-unrelated pattern. In addition, the frequency of the latticelike pattern was relatively low in this series. One possible reason is that some of the cases with peas-in-a-pod pattern were previously classified into the latticelike or parallel furrow pattern with dots because the peas-in-a-pod pattern was not widely known. Another reason could be the low number of AMN located in the arch area in this series, which is a favorite site of latticelike pattern. The investigation of site-related dermoscopic pattern is also required.
According to the revised 3-step dermoscopic algorithm for the management of acral acquired melanocytic lesions,6 lesions without typical benign patterns are considered for biopsy if the maximum diameter is more than 7 mm. The nontypical pattern was increased in the group older than 59 years, suggesting that acral AMN in older patients is more frequently considered for biopsy than in younger patients. Knowledge of age-related dermoscopic pattern is useful when examining melanocytic nevus.
Corresponding Author: Akane Minagawa, MD, Department of Dermatology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto 390-8621, Japan (email@example.com).
Accepted for Publication: February 27, 2013.
Published Online: June 26, 2013. doi:10.1001/jamadermatol.2013.4452.
Author Contributions: Drs Minagawa and Koga had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Minagawa, Okuyama.
Acquisition of data: Minagawa.
Analysis and interpretation of data: Minagawa, Uhara, Yokokawa, Okuyama.
Drafting of the manuscript: Minagawa, Okuyama.
Critical revision of the manuscript for important intellectual content: Minagawa, Uhara, Yokokawa, Okuyama.
Statistical analysis: Yokokawa.
Obtained funding: Okuyama.
Administrative, technical, and material support: Okuyama.
Study supervision: Uhara, Okuyama.
Conflict of Interest Disclosures: None reported.
Funding/Support: This study was supported in part by the National Cancer Center Research and Development Fund (23-A-22).