Clinical Features and Risks of Congenital Melanocytic Naevi: A Retrospective Analysis of Patients at the Queensland...

Congenital melanocytic naevi (CMN) are a risk factor for melanoma. Melanoma risk is dependent on the congenital phenotype. Our primary aims were to assess the clinical characteristics of CMN that indicate a high risk of neurocutaneous melanosis (NCM) and melanoma in an Australian paediatric population group; to identify patient characteristics and clinical features of CMN that trigger further investigations; and to determine the rate of malignancy and other complications for CMN.

We retrospectively reviewed the electronic medical records of all patients under 18 years who were diagnosed with CMN at the Queensland Children's Hospital between 2014 and 2021.

Eighty-eight patients (38 males and 50 females) were included in the analysis. Eighteen patients (20%) had a biopsy to rule out malignancy. Central nervous system magnetic resonance imaging (MRI) was performed in 16 patients (18%). Five patients (5.7%) experienced complications, of which three had NCM and two had transient neurological symptoms with normal MRI. No cases of melanoma, non-melanoma tumours or deaths were recorded.

CMN size, location over the posterior midline axis and multiple numbers of CMN were found to be significantly associated with the development of complications. CMN size, CMN site, presence of satellite naevi and location over the posterior midline axis were all significantly associated with the likelihood of an MRI or biopsy being performed. Large-scale studies, such as a population-based registry, are recommended to accurately assess the true lifetime risk of complications and associated risk factors.