Proliferation features of melanocytic nevi in organ-grafted children

Introduction. Organ-graft recipients are at increased risk for developing c utaneous tumors, mostly carcinomas; however, melanocytic nevi (MN) also dev elop in excess numbers in these patients. The aim of this study was to asse ss whether MN developing in pediatric organ graft recipients (OCR-MN) have a higher proliferative profile than similar lesions developing in non-immun osuppressed subjects (C-MN), a fact that could confer to them potential for malignant transformation into melanoma. Material and methods. The immunohistochemical expression of two proliferati on-associated markers (MIB1/Ki67 and PCNA) and of p53 oncoprotein was compa ratively studied in a group of 10 and OGR-MN and 12 C-MN. Results. MIB1/Ki67 and p53 were very weakly, if at all, expressed in all tu mors, whereas PCNA was expressed in the majority of tumor cells in both gro ups of lesions. Overall, no significant differences were found between the two groups studied. Discussion. Melanocytic nevi developing in organ transplant children do not have a higher proliferative potential, and therefore do not seem to be int rinsically more prone to malignant transformation than similar lesions appe aring in non-immunosuppressed children; however the possibility exists that the decreased immune defense mechanisms indirectly favors the growth of th ese lesions.