Melanoma in congenital melanocytic naevi

Abstract

SummaryCongenital melanocytic naevi (CMN) are a known risk factor for melanoma, with the greatest risk currently thought to be in childhood. There has been controversy over the years about the incidence of melanoma, and therefore over the clinical management of CMN, due partly to the difficulties of histological diagnosis and partly to publishing bias towards cases of malignancy. Large cohort studies have demonstrated that melanoma risk in childhood is related to the severity of the congenital phenotype. New understanding of the genetics of CMN offers the possibility of improvement in diagnosis of melanoma, identification of those at highest risk, and new treatment options. We review the world literature and our centre's experience over the last 25 years, including the molecular characteristics of melanoma in these patients and new melanoma incidence and outcome data from our prospective cohort. Management strategies are proposed for presentation of suspected melanoma of the skin and the central nervous system in patients with CMN, including use of oral mitogen‐activated protein kinase kinase inhibitors in NRAS‐mutated tumours.

Clinical and dermoscopic characteristics of congenital melanocytic naevi

“…However, although rare, lethal melanomas have been reported in prepubertal children arising in small and medium CN . Although melanoma in large nevi originates from the deep dermis or subcutis, presenting as a nodule or lump, melanomas in small and medium CN typically arise at the dermal–epidermal junction, manifesting as changes in colour and shape of the naevus, which can be detected dermoscopically . Dermoscopy therefore is an important tool in the management of CN and can be used in the regular follow‐up of those nevi in order to detect early melanomas.…”

MelaNostrum: a consensus questionnaire of standardized epidemiologic and clinical variables for melanoma risk assessment by the melanostrum consortium

“…43,44 The identification and recording of common melanocytic and atypical nevi-two well-established risk factors associated with a high risk of melanoma-proved to be one of the most difficult tasks in the epidemiologic investigation of melanoma. [55][56][57][58][59] Section D of MelanoQ contains highly structured questions regarding patient melanoma diagnosis, including anatomical site of the lesion, tumour histopathologic features and tumour mutational status information (if applicable). Before deciding how to collect nevi data, the MelaNostrum clinicians discussed the diagnosis and measurement criteria, reviewed the abundant literature on the topic 12,22,23,[45][46][47] and addressed the inter-observer differences in nevus count.…”

Management of congenital melanocytic nevi in the plastic surgery clinic: Families′ expectations and their persistent concern about malignancy

“…The term congenital melanocytic nevi (CMN) refers to clonal proliferations of benign melanocytes that are present at birth but may not become apparent until the first few months of life . The incidence rate ranges between 1%‐2% for small and 1:20 000 for so‐called giant lesions (CMN larger than 40 cm in diameter based on their projected adult size [PAS]) . The two life‐threatening complications associated with CMN are neurocutaneous melanocytosis (NCM) and melanoma (MM) …”

“…MM risk in CMN patients is now believed to be significantly lower with less than 1% for small‐ and medium‐sized CMN, and under 5% for giant CMN . Furthermore, a significant number of MM were shown to arise outside the CMN . Those studies have fueled a paradigm shift in CMN management: Surgical excision is no longer the treatment of choice, unless malignancy is confirmed, which is rare .…”