A Case of Blue Nevus Mimicking Malignant Melanoma Within a Keloid Scar

Blue nevus is a type of melanocytic nevus which clinically presents itself as blue/gray plaque or nodule. It most commonly develops upon distal extremities especially dorsal hands and feet, trunk and scalp. Histopathologically, heavy melanocyte aggregations in the deep dermis result in blue nevus formation. Different types of blue nevus include common blue nevus, cellular blue nevus, plaque-type blue nevus, combined blue nevus, desmoplastic blue nevus and subungal blue nevus. Although clinical findings may be sufficient to diagnose blue nevus, dermoscopy could be used as a helpful tool to aid in reaching the correct diagnosis. Dermoscopy usually shows diffuse blue-gray structureless area but since atypical clinical and dermoscopical features may be observed, histopathological diagnosis is the definitive step to differentiate blue nevus from its mimickers such as malignant melanoma. We want to present an interesting case of blue nevus mimicking malignant melanoma developing in a scar.