[Proliferative characteristics of nevus in children with organ transplants].

Introduction: Organ-graft recipients are at increased risk for developing cutaneous tumors, mostly carcinomas; however, melanocytic nevi (MN) also develop in excess numbers in these patients. The aim of this study was to assess whether MN developing in pediatric organ graft recipients (OGR-MN) have a higher proliferative profile than similar lesions developing in non-immunosuppressed subjects (C-MN), a fact that could confer to them potential for malignant transformation into melanoma.
Material and Methods: The immunohistochemical expression of two proliferation-associated markers (MIB1/Ki67 and PCNA) and of p53 oncoprotein was comparatively 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 tumors, whereas PCNA was expressed in the majority of tumor cells in both groups 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 intrinsically more prone to malignant transformation than similar lesions appearing in non-immunosuppressed children; however the possibility exists that the decreased immune defense mechanisms indirectly favors the growth of these lesions.