[505] Immunohistochemical Profile Distinguishes Spitz Nevi from Melanomas

MC Garrido-Ruiz, L Requena, P Ortiz, B Perez-Gomez, JL Rodriguez-Peralto. 12 de Octubre University Hospital, Madrid, Spain; Fundacion Jimenez Diaz University Hospital, Madrid, Spain; National Center for Epidemiology, Carlos III Institute of Health, Madrid, Spain

Background: Several isolated markers have been proposed to aid in differential diagnostic of difficult melanocytic lesions, albeit none has been demonstrated definitive in differentiating Spitz nevus from melanoma.
Design: This study proposes a wide panel of 22 markers playing key roles in different biological functions including cell cycle regulators, apoptotic markers, DNA repair proteins and membranous receptors in order to provide a combination of proteins associated with either benign or malignant phenotype. Using tissue microarrays, we compared protein expression profiles in 28 typical Spitz nevi and 62 primary vertical growth phase non-spitzoid melanomas.
Results: Most of the significant differences were linked to cell cycle deregulation such as over-expression of cyclin D1 and p21 in Spitz nevi compared to non-spitzoid melanomas (74% vs. 16%: p<0.005 and 91% vs. 27%; p<0.005 respectively) and mitotic rate including Ki-67, highly expressed in deep areas of non spitzoid melanomas (37%) whereas Spitz nevi didn't express it (0%: p<0.005), topoisomerase IIα (79% in non-spitzoid melanomas versus 15% in Spitz nevi, p<0.005) and nuclear survivin (69% in melanomas versus 0% in Spitz nevi, p<0.005). In addition, osteonectin (SPARC) and protein kinase Cα (PKCα), previously well recognized to have an important role in local invasion, have shown to be significantly overexpressed in Spitz nevi (96% for both markers) compared to melanomas (43% and 48% respectively).


Conclusions: The study defines a combination of biological markers differentially expressed in Spitz nevi from non-spitzoid melanomas providing a potential tool for histopathological differential diagnosis between Spitz nevus and melanoma. Nevertheless, more studies including atypical Spitz nevi and spitzoid melanomas are necessary to further establish a reliable panel to differentiate among difficult cases.
Category: Dermatopathology

Wednesday, March 24, 2010 1:00 PM

Poster Session VI # 76, Wednesday Afternoon

 

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