Clinical and Dermoscopic Features of Surgically Treated Melanocytic Nevi: A Retrospective Study of 1046 Cases
Melanocytic nevi (MN) are common skin lesions that can be classified as congenital or acquired. Congenital MN are present at birth or appear within the first two years of life, while acquired MN develop throughout childhood and adulthood, peaking in the third decade. These nevi are classified histologically into junctional, intradermal, and compound subtypes based on the location of melanocyte nests. The risk of malignant transformation varies among these subtypes, making their clinical and dermoscopic evaluation crucial for early melanoma detection. This study aimed to characterize the clinical and dermoscopic features of MN in Chinese patients, a population for which such data are limited.
Study Design and Methodology
This retrospective study analyzed 1046 cases of MN surgically treated at the Department of Dermatology and Venerology, Peking University First Hospital, from January 1 to December 31, 2014. Clinical data, including patient demographics, lesion location, history, and histologic findings, were collected. Dermoscopic images were reviewed by three experienced dermatologists. Statistical analyses were performed to examine associations between lesion location, histologic subtypes, and dermoscopic patterns. Ethical approval was obtained, and informed consent was waived due to the retrospective nature of the study.
Clinical and Demographic Features
The study population consisted of 740 females (70.8%) and 306 males (29.2%), indicating a female predominance across all lesion locations. The age at which nevi first appeared ranged from birth to 79 years, with 83.2% of cases developing nevi before the age of 30. Congenital nevi accounted for 36.4% (381/1046) of cases, with 81.6% (311/381) present at birth. The majority of congenital nevi were small (<1.5 cm) and located on the head and neck region (50.4%).
The most common reasons for seeking surgical removal were concerns about malignant transformation (58.1%) and cosmetic issues (31.6%). Most nevi were asymptomatic, with only 2.5% of patients reporting symptoms such as pruritus or pain.
Growth Patterns of Nevi
The study examined the length growth rate of nevi, calculated as the ratio of lesion length at presentation to length at onset. The median growth rate for congenital nevi was 2.0, compared to 1.6 for acquired nevi. When stratified by age, congenital nevi showed the highest median growth rate (2.2) in the 0–9 years age group, suggesting rapid growth during early childhood. Growth rates stabilized in older age groups, with median values of 2.0, 2.4, and 2.0 for the 10–19, 20–29, and ≥30 years age groups, respectively.
Histologic Subtypes and Lesion Location
Histologic analysis revealed that intradermal nevi were the most common subtype (67.4%), followed by compound (25.1%) and junctional nevi (7.6%). However, in acral locations (palms, soles, and nails), junctional nevi were predominant (50.2%), followed by compound (37.8%) and intradermal nevi (12.0%). Statistical analysis confirmed a significant association between acral location and junctional nevi (odds ratio [OR]: 91.572, 95% confidence interval [CI]: 52.210–160.959, P < 0.05). Acral location was also associated with a higher likelihood of compound nevi (OR: 14.468, 95% CI: 8.981–23.306, P < 0.05).
Dermoscopic Features
Dermoscopic patterns varied by lesion location. On the head and neck, the globular pattern (59.4%) and pseudonetwork pattern (48.8%) were most frequently observed. In non-acral regions (trunk and nonglabrous extremities), the globular pattern (34.8%) remained the most common, followed by the homogeneous pattern (21.1%). A pure reticular pattern was rare, occurring in only 6.9% of cases.
In acral nevi, the parallel furrow pattern (46.0%) was the most common, followed by the fibrillar pattern (21.7%). The irregular blotch pattern was frequently observed in nevi with dermal components, particularly in intradermal nevi (62.5%). The parallel furrow pattern was common in both junctional and compound nevi, while the irregular blotch pattern was predominant in intradermal nevi.
Discussion
This study provides a comprehensive analysis of the clinical and dermoscopic features of MN in Chinese patients, highlighting unique characteristics compared to other populations. The female predominance in the study population suggests a greater concern for skin health and appearance among women. The high prevalence of congenital nevi on the head and neck region may reflect increased visibility and subsequent patient anxiety.
The growth patterns of congenital nevi, particularly the rapid growth observed in early childhood, provide valuable insights for patient counseling. The stabilization of growth rates in older age groups supports a conservative approach to small and medium-sized congenital nevi unless malignancy is suspected. For large and giant congenital nevi, early removal may be beneficial due to skin elasticity and ease of closure.
The histologic distribution of MN in this study aligns with previous reports, with intradermal nevi being the most common subtype overall. However, the predominance of junctional nevi in acral locations underscores the importance of careful evaluation of acral lesions, given their potential for malignant transformation.
Dermoscopic findings revealed distinct patterns based on lesion location. The globular pattern, which is uncommon in older Caucasian patients, was prevalent across all age groups in this study. This suggests that the presence of a globular pattern in older Chinese patients may be less concerning and less likely to warrant biopsy. The polymorphous blood vessel pattern, often considered a sign of malignancy, was frequently observed in benign dermal nevi, particularly on the head and neck.
Limitations
The study has several limitations. The selection bias inherent in analyzing only excised nevi may limit the generalizability of the findings. Additionally, the retrospective nature of the study resulted in some missing data, and the estimation of lesion length at onset by patients may have introduced inaccuracies. Finally, as a single-center study, the results may not fully represent the broader Chinese population.
Conclusion
This study highlights the unique clinical and dermoscopic features of MN in Chinese patients, providing valuable insights for dermatologists. Understanding these differences is essential for accurate diagnosis and management of melanocytic lesions in ethnically diverse populations. The findings emphasize the importance of patient education regarding MN and melanoma risk, as well as the need for further research to validate these observations in larger, multicenter studies.
doi.org/10.1097/CM9.0000000000000416
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