Melanoma Arising in Blue Nevus

Melanoma can develop in a blue nevus. The blue nevus is generally a “cellular” variant (common and cellular are oversimplifications, as there are many more patterns of blue nevus than these), but there are a few recorded cases of malignant change in sparsely cellular dermal melanocytoses such as Ota nevus. In order to make a diagnosis of melanoma arising in a blue nevus, the basic histological characteristics of the latter must be recognizable at the periphery of the lesion, or (less satisfactory) a previous biopsy should unequivocally show a benign blue nevus.