Differential Clinicopathological Features in Spontaneous Regression of Melanomas and Melanocytic Naevi

Abstract

The aim of this study was to determine the clinical, histological and/or immunohistochemical features that enable differential diagnosis of regression of melanocytic naevi from regression of melanomas. All melanocytic neoplasms with histologically-confirmed regression diagnosed in our hospital between 2002 and 2009 were reviewed retrospectively. Lamellar and delicate fibrosis were associated with melanocytic naevi (p<0.0001 and p=0.021, respectively). Compact fibrosis, high vessel density and higher number of granzyme B+ lymphocytes were associated with malignant melanoma (p=0.011, p=0.005 and p=0.013, respectively). Density of inflammatory infiltrate (p=0.016), vascular proliferation (p=0.005), epidermal atrophy (p=0.009), rate of apoptosis (p=0.046) and granzyme B immunoreactivity (p=0.013) was more common in severe?dysplastic naevi and melanomas than in the remaining melanocytic naevi. Logistic regression demonstrates that 5 variables (age, lamellar fibrosis, melanophages, vessel density, and granzyme B immunostaining) would serve to classify appropriately 87% of melanomas among melanocytic lesions with complete regression.