Reply

Sir: Thank you for allowing us to respond to the letter addressing our article. We are actually quite impressed that the article has generated such interest and underscores its importance. The letter is written by authorities in the field of congenital melanocytic nevi and needs to be heard. We are pleased to respond. First, the authors claim that we base our current treatment philosophy on the opinion of one institution and one clinician. Our treatment algorithm is in fact based on data from several studies and several institutions, including our own. We conclude the following: The risk of melanoma in patients with giant congenital melanocytic nevi is generally higher than in the general population (0.7 to 2.9 percent versus 0.6 percent). Patients with giant congenital melanocytic nevi of the trunk or multiple satellite lesions have the highest risk and may account for most of the elevated risks mentioned (patients with lesions of the head and extremities run a low risk). There is no proof that surgery lowers the risk for melanoma. We quoted two systematic reviews, by Krengel et al.1 and by Watt et al.2 Both reviews demonstrate an association between large lesion size and high risk of melanoma. Krengel et al. state that this risk is highest in “garment lesions” of the trunk. Neither review showed any evidence of a positive impact of prophylactic surgery on the risk of melanoma. They explain the limitation of performing statistical analysis on a group of studies that differ from each other in description of lesion location, lesion size, and type of surgery. We are criticized for quoting the studies by Kinsler et al.3–5 These studies rely on patients who were referred by physicians to participate in the study at Great Ormond Street Hospital, one of the finest pediatric hospitals in the world, after definite diagnosis of congenital melanocytic nevus by a dermatologist. The patients provided answers to an annual questionnaire, and over 300 patients were followed for a median of 9 years. Kinsler et al. report five cases of melanoma (1.4 percent), all occurring in patients with congenital melanocytic nevi larger than 60 cm of the trunk or multiple lesions, and all with satellite lesions at birth. This is supported by studies such as the Registry of Large Congenital Melanocytic Nevi of the New York University School of Medicine that we will refer to later. Second, the letter states that our “data cannot be relied on as scientifically accurate,” because it was obtained through parent questionnaires. To be clear, these questionnaires were largely seeking factual information, such as the size of the nevus, number of satellite lesions, development of new areas of the nevus, and others. This factual information is indeed valid and, considering the size of the cohort and the length of the study, provides very worthwhile information. Features such as cosmesis or worthiness of surgery may be too subjective to be scientifically sound, but we did not infer this, nor was it the primary focus of the study. The Registry of Large Congenital Melanocytic Nevi of the New York University School of Medicine studies,6,7 coauthored by Dr. Marghoob (who by the way is a signatory to the letter criticizing our article), are also based on information obtained from physicians who initially provided the data for entering their patients into the registry. They state that “follow-up information was obtained through mailed questionnaires, telephone calls and/or email from the physicians who initially enrolled the patients into the registry, from the patients themselves, or from other relatives or caregivers.” Does this invalidate the study or its findings, as suggested by the authors of the letter? We do not think so! In fact, it provides valuable information regarding the location of the development of melanoma, with nine of the 10 patients having a congenital melanocytic nevus in the trunk and no melanomas arising in lesions of the head or extremities. Third, the letter criticizes our article for quoting articles that infer that surgery may have adverse effects on congenital melanocytic nevus cells. It is well known that these lesions change over time in their color and surface characteristics. We simply do not know what occurs to the cells when they are manipulated, either by laser, dermabrasion, or incomplete surgical excision. Nowhere in our article do we write that surgical treatment for congenital melanocytic nevus raises the risk of melanoma. To be fair, although Kinsler et al. raise concerns of possible adverse outcomes resulting from melanocytic activation by surgery, she states that she found no significant effects of having treatment, treatment timing, or type, on neurologic outcomes, tumors, melanoma, or death. It should be noted that Kinsler is a world authority in the field of congenital melanocytic nevi, her research is very highly regarded, and her opinions should be considered seriously. In the Registry of Large Congenital Melanocytic Nevi of the New York University School of Medicine series, treatment methods included complete excision (12 percent) or partial removal (46 percent) using direct closure, grafting, tissue expansion, dermabrasion, or a mix of the above procedures. They found no association between the treatment of large congenital melanocytic nevi and the development of melanoma. Marghoob et al.8 refer to the findings in this study and the Swedish birth registry sample study.9 They explain the low incidence of melanoma in both (4.9 percent and 0 percent, respectively) by the relatively high rates of surgery (58 percent and 40 percent, respectively). However, we feel this is a difficult conclusion to draw amidst the diversity in type and extent of treatments and particularly the absence of a control group. It is emphasized in our article that we too favor surgical excision of giant congenital nevi of the trunk, because they appear to have a higher risk for melanoma. We disagree with the claim that our article “serves to spread misinformation to the lay public, which in turn creates a barrier hindering rational discussion of treatment options.” Rational discussion should be based on the understanding that some congenital melanocytic nevi have higher risks than others, and that surgery does not necessarily improve outcomes. We suggest that these unsolved issues and others pertaining to congenital melanocytic nevi be looked at in a scientifically valid, prospective, multicenter study. Our unit would welcome such a collaborative effort, as it would provide factual data in the management of our patients. Once again, we thank you for the opportunity to respond. DISCLOSURE The authors have no financial interest to declare in relation to the content of this communication. Ehud Arad, M.D. Ronald M. Zuker, M.D. The Hospital for Sick Children Toronto, Ontario, Canada

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