Pleiotrophin expression correlates with melanocytic tumor progression and metastatic potential

Background: Gene expression profiling of melanoma and nevic tissue has demonstrated that pleiotrophin (PTN) is significantly overexpressed in human melanomas. Methods: To further evaluate PTN expression in melanocytic lesions, protein immunohistochemistry was performed on the spectrum of melanocytic lesions. Results: Melanocytic nevi were consistently negative (n = 58). In contrast, the great majority of metastatic melanomas were positive (33/34, 97%). The analysis of 34 primary melanomas demonstrated PTN positivity in 20 lesions while 14 lesions were negative. Within the primary melanomas, PTN immunoreactivity was associated with metastasis (p = 0.0004) and decreased melanoma-related survival (p = 0.0444). Univariate analysis of PTN immunoreactivity predicted an increased risk for metastasis (relative risk 9.1, p = 0.003). Conclusions: The results of this study confirm previous gene profiling data showing differential PTN expression between melanocytic nevi and melanomas. In addition, lesional PTN expression is associated with metastatic potential and may be a prognostic factor for melanomas.