Congenital melanocytic nevus: an epidemiologic study in Italy

The prevalence of congenital melanocytic nevi (CMN) among newborns ranges between 0.2 and 6% in the worldwide literature. In the only available study from Italy the rate was 1% at birth and 1.4% at 2 years of age. Some surveys performed among samples of children and adolescents in other countries showed a prevalence which ranged from 1.4 to 4.4%. Additional data on the frequency in adults are not available.

The aim of this study was to estimate the prevalence of CMN in a large sample of a young male Italian population, which is deemed to be representative of the general population of the same age and sex.

The potential conscripts resident in the coastal regions of southern Italy, enlisted for the compulsory service in the Italian Navy, were called at the age of 18 to the Draft's Council Medical Unit of the Italian Navy in Taranto to evaluate their psychophysical fitness to recruitment. All the subjects examined from September 2002 to March 2004 showing skin lesions evocative of CMN were referred by general practitioners of the Draft's Council Medical Unit to the Department of Dermatology of the Italian Navy Hospital for confirming the diagnosis, which was based on the clinical features and the personal history. The confirmed cases were recorded in a predefined patient card, containing the main anamnestic and clinical data. Since the screening of small CMN in such a large sample of subjects was believed to be difficult, only CMN with a diameter >or=1.5 cm were recorded.

In 23,354 examined persons 157 CMN were diagnosed, with a prevalence of 0.67% (Bayesian 95% confidence interval 0.57-0.79); 126 (80.3%) CMN were medium-sized (>or=1.5 and or=20 cm in diameter). Three CMN (1.9%) were located on the face, 23 (14.6%) on the chest, 24 (15.2%) on the abdomen, 36 (22.9%) on the back, 48 (30.5%) on the lumbar area, 15 (9.5%) on the upper limb, 19 (12.1%) on the lower limb and 15 (9.5%) on the shoulder. No CMN was located on the head. In 19 cases (12.1%) >or=2 adjacent anatomical sites (shoulder/chest, shoulder/arm, etc.) were involved. In 73 moles (46.4%) terminal hairs were present. Eight CMN (5.1%) showed a zosteriform (i.e. segmental) feature. None of the examined subjects reported a personal history of malignant melanoma (MM), and no person with a history of MM was observed among all the enlisted men referred to the Department of Dermatology during the time of the study.

The prevalence of CMN in the Italian young male general population is roughly in agreement with the rates detected in general populations from other European studies. The observations of this study also suggest that the risk of appearance of MM, at least in childhood and adolescence, is limited for medium-sized CMN.