Partial Histological Tumor Regression in Primary Melanoma as Protective Factor for Lymph Node Micrometastasis

Partial histological tumor regression in primary melanoma is a rather frequent event and has been reported in 10% to 35% of primary melanomas. Partial histological tumor regression is defined as an area within the tumor where melanoma cells have disappeared and are substituted by scarring and melanophages.¹ Clinically, a skin-colored or depigmented area develops within the tumor. Regression is a clinical and dermoscopic criterion for the melanoma diagnosis. Partial tumor regression with scarring does not occur in benign melanocytic nevi.