Management of large congenital melanocytic nevi: art versus science.

T he management of large congenital melanocytic nevi (LCMN) has received significant attention in the medical literature during the past decade. Unfortunately, this is a topic where the ‘‘art’’ of medicine has filled the void created by the lack of ‘‘science.’’ One of the problems with collecting data regarding therapeutic options in LCMN is that the condition is rare. The ‘‘watch and wait’’ approach may be acceptable for smalland medium-sized congenital nevi, where melanomas typically develop superficially. In addition, malignant transformation of smalland medium-sized congenital nevi is virtually nonexistent in prepubertal age groups. However, in patients with LCMN, melanomas are typically of non-epidermal origin, developing deep in the dermis, subcutaneous tissue, or leptomeningeal tissues in as many as two thirds of patients. Therefore, some feel that close observation is not as effective in detecting melanoma in patients with LCMN, because tumors may be more advanced by the time they become clinically evident. Most manuscripts state that patients with LCMN have an increased risk of developing malignant melanoma (MM), neurocutaneous melanocytosis (NCM), or other complications. While previously published data suggest a 5% to 15% lifetime risk of developing MM, these rates may be exaggerated because of referral bias. One of the challenges facing clinicians is the reduction of the risk of MM in these patients. Can surgical removal of these lesions lower patients’ risk of developing MM? Unfortunately, a critical review of the current literature does not provide an answer to this question. Some studies have attempted to compare the incidence of MM in LCMN patients treated with excision versus simple observation. However, most of these studies have been underpowered, making statistically sound recommendations impossible. In addition, many of these studies are retrospective in nature, and referral bias is inherent in series published from tertiary referral centers. The largest series of patients with LCMN followed in the United States is from the Registry of Large Congenital Melanocytic Nevi of the New York University School of Medicine (NYU-LCMN Registry). Of the 205 patients with LCMN from this registry reported by Hale, the presence of numerous satellite lesions was associated with the occurrence of melanoma, but surgical excision versus observation did not affect the risk of developing melanoma. Unfortunately, the data presented did not indicate the timing of surgery in these patients, so it is difficult to draw meaningful conclusions. However, while 4 of the 170 patients from this registry who were followed prospectively developed extracutaneous melanoma (median follow-up: 5.3 yrs), it is interesting that none of these prospectively followed patients developed a melanoma in their LCMN. While the risk of cutaneous melanoma has always been a feared complication of LCMN, an equal or greater risk to these patients may be extracutaneous involvement, particularly neurocutaneous melanosis. The NYU-LCMN Registry actually contains more cases of NCM than of melanoma (17 cases vs 10 cases). Removal of LCMN is not recommended in patients with symptomatic NCM, as the prognosis is poor, and no effective therapy is currently available. Recently, Bett reported findings from 1008 patients with LCMN or multiple congenital melanocytic nevi who voluntarily enrolled themselves (or their children) into the Nevus Network, a large database formed in 1983. Of the 525 patients with garment LCMN in whom follow-up data was available, 15 (2.9%) developed cutaneous melanoma. All cases of From the Division of Dermatology, Santa Clara Valley Medical Center, San Jose, and the Department of Dermatology, Stanford University School of Medicine. Funding sources: None. Conflicts of interest: None identified. Reprints not available from the author. Correspondence to: Matthew H. Kanzler, MD, Division of Dermatology, Santa Clara Valley Medical Center, 751 S Bascom Ave, San Jose, CA 95128. E-mail: [email protected]. J Am Acad Dermatol 2006;54:874-6. 0190-9622/$32.00 a 2006 by the American Academy of Dermatology, Inc. doi:10.1016/j.jaad.2006.03.005