Objectives:

Congenital melanocytic nevi (CMN) are the melanocytic nevi present at birth. Clinical and dermoscopic signs and findings of these nevi diverge from those of acquired nevi. While large CMN bear greater malignant transformation risk, macroscopically surface irregularities and very dark pigmentations reveal atypical appearance. Therefore , it is important to be familiar with characteristic macroscopic and dermoscopic features. Dermoscopic studies on CMN are relatively limited. The aim of the study is to document demographic features for CMN like age and sex along with clinical features such as localization, size, surface qualities, and also dermoscopic features of CMN, and finally, to assess the relation between dermoscopic, demographic and clinical data.

Methods:

46 patients (21 men, 25 women) at 5-63 years of age with CMN were recruited for the study and 46 nevi were assessed. The data was attained by personal history and/or by information provided by parents. All these nevi were examined clinically and dermoscopically. After the clinical photographs were taken, location, size and surface characteristics were recorded. Dermoscopic findings were evaluated regarding pattern, presence of hairs, scale and vessel structures. Also, unusual findings were recorded.

Results:

24 (52.1%) nevi were smaller than 1,5 cm, 21 lesions (45.6%) were 1,5-20 cm, only one lesion was larger than 20 cm in diameter. 19 nevi located on the extremities, 14 on the trunk, 13 on the head and neck. Predominant dermoscopic patterns were reticular (36.9%), diffuse pigmentation (19.5%), globular (15.2%), cobblestone (13.0%), reticuloglobular (6.52%) and pseudo-network (4.34%). As there was no predominant pattern in two lesions (4.34%), they were evaluated as “indeterminate pattern”. Cobblestone pattern was commonly seen in smaller CMN whereas diffuse pigmentation was frequently seen in medium- sized CMN. Other dermoscopic findings were hypertrichosis, perifollicular hypopigmentation, scale ,milia-like cysts and vessel structures.

Conclusion:

Clinically, small size and the presence of hairs were common. Dermoscopically, the most frequent pattern was the reticular pattern heavily seen with subjects at 11-50 years old at both extremities and trunk. Perifollicular hypopigmentation and indeterminate patterns appeared to be particular for CMN. Scale was an additional feature seen in most nevi.

Keywords: congenital nevi , dermoscopy, melanocytic nevi