Large congenital melanocytic nevi are cutaneous lesions regarded by many as premalignant; estimates of malignancy incidence range from 0 to 42 percent. Given the often complex and extensive nature of large congenital melanocytic nevi resection and reconstruction, the risk of malignant transformation is a crucial factor that surgeons and families must weigh when deciding whether or not to excise the lesion. The authors conducted a systematic analysis of data from the existing literature to critically evaluate the published studies and to establish a crude incidence rate for the risk of malignant melanoma transformation in large congenital melanocytic nevi. After a comprehensive literature search, they analyzed data from eight studies (containing a total of 432 large congenital melanocytic nevi patients) of sufficient scientific quality. Twelve patients (2.8 percent) in this sample developed cutaneous malignant melanoma during the reported follow-up periods. Using a subset of this data and comparing the incidence rates to those of the Surveillance, Epidemiology, and End Results population-based database using a standardized morbidity ratio, the authors found that the large congenital melanocytic nevi patients had an increased risk of melanoma (standardized morbidity ratio, 2599; 95 percent confidence interval, 844 to 6064) compared with the general population. Regarding treatment before developing melanoma in the 12 patients, 50 percent were observed before diagnosis, 17 percent had partial excision, 8.3 percent had dermabrasion, 8.3 percent had a chemical peel, and 17 percent did not have any treatment information. These combined data are clinically useful when consulting with the parents of children with large congenital melanocytic nevi and in the management of older patients with existing lesions. This study shows that there is a significantly increased risk of melanoma in large congenital melanocytic nevi patients. The data also reveal the need for a standardized definition of large congenital melanocytic nevi and a long-term, prospective outcomes study to determine the true lifetime risk of melanoma in patients with and without surgical excision.
Summary1. Two preparations, a segment of the ileum and the myenteric plexuslongitudinal muscle preparation, have been used for an analysis of the inhibitory effects of adrenaline, noradrenaline and isoprenaline on the contractor responses of the longitudinal muscle to acetylcholine or to electrical, coaxial or field, stimulation. 2. Since the inhibitory effects of adrenaline, noradrenaline and isoprenaline on the acetylcholine-induced contractions were not affected by phenoxybenzamine but were antagonized by propranolol, it is concluded that 3-adrenoceptors are present on the muscle cells. 3. The responses to electrical stimulation were suppressed by adrenaline or noradrenaline but only partly inhibited by isoprenaline. Propranolol antagonized the effect of isoprenaline and, to some extent, that of noradrenaline, but scarcely affected the action of adrenaline. Phenoxybenzamine, on the other hand, antagonized most of the effect of adrenaline and, to some extent, that of noradrenaline; it usually potentiated the effect of isoprenaline. 4. The output of acetylcholine evoked by electrical stimulation was diminished by adrenaline or noradrenaline but was not affected by isoprenaline. The depressant effect on acetylcholine release was antagonized by phenoxybenzamine but not affected by propranolol ; therefore these effects of adrenaline and noradrenaline are mediated by a-adrenoceptors. 5. It may be assumed that a-adrenoceptors in situ are stimulated mainly by circulating adrenaline and possibly noradrenaline and thus cause a prejunctional inhibition at the nerve-smooth muscle junction.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.