CASE SERIES Clinical characteristics and risks of large congenital melanocytic naevi: A review of 31 patients at the Sydney Children’s Hospital Andrew Chih-Chieh Chen, 1,2 Michelle Yvonne McRae 3 and Orli Wargon 4 1 Department of Dermatology, Royal Prince Alfred Hospital, 2 Montrose Medical Practice, 3 Department of Dermatology, Westmead Hospital, and 4 Department of Dermatology, Sydney Children’s Hospital, Sydney, New South Wales, Australia ABSTRACT Large congenital melanocytic naevi (LCMN) are asso- ciated with an increased risk of malignancy and neu- rocutaneous melanocytosis (NCM). This Australian study aims to assess both the clinical characteristics of LCMN and the risks associated with it. The authors reviewed medical records of the Sydney Children’s Hospital Dermatology Outpatient Clinic for the past 10 years and identified 31 eligible patients. A total of 14 boys and 17 girls with a median age of 0.13 years were assessed; 18 lesions were on the trunk, five were on the head, five were on the lower limbs and three were on the upper limbs. In all 20 patients had satellite naevi (the median number of the satellite naevi was 7.5). The patients were followed up for a median duration of 12 months. Central nervous system magnetic reso- nance imaging was performed on 19 patients and two (6.5%) were found to have NCM. Biopsies were per- formed on five patients; one patient (3.2%) was found to have benign proliferative nodules of undifferenti- ated spindle cells but no patient (0%) was found to have a malignancy. The clinical characteristics for the two patients with NCM and the patient with benign proliferative nodules suggest that the risk of both NCM and benign proliferative nodules may be greater with an increased number of satellite naevi and with the LCMN being larger in size. Key words: large congenital melanocytic naevi, neurocutaneous melanocytosis, prolifera- tive nodule. INTRODUCTION Congenital melanocytic naevi (CMN) are benign lesions that develop in utero and consist of nests of melanocytes. The diagnosis of CMN is typically clinical; however, there are histological features that can be identified in most cases. 1 CMN vary in size, from small to giant CMN that cover most of an individual’s body surface. There are different classification systems according to the size of the CMN but the most universally accepted system is that used by the New York University Registry. 2,3 Large CMN (LCMN) are lesions that are predicted to attain at least one diameter of no less than 20 cm by adulthood. LCMN are present in approximately 1 in 20 000 newborns. 4 There have been studies that confirm an increased risk of malignancy in individuals with LCMN. 3,5–10 The magnitude of the risk for LCMN varies widely between studies; the data from well- conducted studies, however, suggest an estimated risk in the order of 2–5% during their follow up. 3,5,9 The highest risk of developing malignancy for patients with LCMN is in the first 3 years of life. 3 Complications from LCMN include cuta- neous melanoma, leptomeningeal melanoma, neurocuta- neous melanocytosis (NCM), benign proliferative nodule and other tumours such as sarcoma. The goal of this study was to review an Australian expe- rience of the clinical characteristics and the risks of LCMN in the first few years of life, when the risk of malignancy is greatest, and when it’s important that NCM is excluded. MATERIALS AND METHODS We reviewed medical records of the Sydney Children’s Hospital Dermatology Outpatient Clinic for the previous Correspondence: Dr Andrew Chih-Chieh Chen, Department of Dermatology, Royal Prince Alfred Hospital, Camperdown, NSW 2050, Australia. Email: andrewchen78@gmail.com Andrew Chih-Chieh Chen, FRACGP. Michelle Yvonne McRae, MBBS (Hons). Orli Wargon, FACD. Submitted 9 February 2012; accepted 4 March 2012. Abbreviations: CMN congenital melanocytic naevi CNS central nervous system FISH fluorescence in situ hybridization LCMN large congenital melanocytic naevi MRI magnetic resonance imaging NCM neurocutaneous melanocytosis Australasian Journal of Dermatology (2012) ••, ••–•• doi: 10.1111/j.1440-0960.2012.00897.x © 2012 The Authors Australasian Journal of Dermatology © 2012 The Australasian College of Dermatologists