The nature of Spitz nevi is poorly understood, and their distinction from malignant melanoma can be difficult. Although there is general agreement on the diagnostic criteria, experts continue to have some differences, and controversial cases are not rare. A major obstacle to progress in this area is the lack of basic knowledge about melanocyte differentiation in Spitz nevi, as compared with ordinary nevi and malignant melanomas. Based on the hypothesis that normal melanocytes may have a differentiation pathway with discrete stages, it is suggested that the features of Spitz nevi may reflect homeostatic mechanisms governing maturation in the melanocyte differentiation pathway, whereas those of malignant melanomas may reflect carcinogen-induced aberrations. This perspective may be helpful in the continuing effort to develop optimal criteria for the differential diagnosis of Spitz nevi from malignant melanomas.
From the Department of Pathology, Rochester General Hospital, University of Rochester School of Medicine, Rochester, New York, U.S.A.
Address correspondence and reprint requests to Dr. S.F. Cramer, Department of Pathology, Rochester General Hospital, 1425 Portland Avenue, Rochester, NY 14621, U.S.A.
The results of this work were presented in part at the meeting of the Society for Pediatric Pathology, Washington, DC, September 19, 1987.