Immune response in a regressing compound dysplastic nevus

Atypical (dysplastic) melanocytic nevi are considered for many as an intermediate step in a clinicopathologic spectrum. Regression is often seen. A 45 year old male presented with a hyperpigmented macule on the patient’s back. Biopsies for hematoxylin and eosin (H&E) examination and immunohistochemistry (IHC) analysis were performed. The H&E staining demonstrated a compound dysplastic nevus. IHC stain shows stains with galectin 3, CD45, B-cell lymphoma 2 cyclooxygenase-2 ribosomal protein S6-ps240 (RIBO), CD68 and tyrosinase. Some stains were not only present in the tumor, but around it. We described a case of compound dysplastic nevi with a likely effectual early antitumoral response avoiding the growth to melanoma. The fundamental mechanism has not been elucidated, but our findings indicate a mix of inflammatory as well as immune response mediators maybe involved in the immune-based obliteration of melanocytes