[Malignant infiltrating blue nevus of the plaque type. Case report and literature review].

We present, to the best of our knowledge, the first case of a malignant, primary plaque-type blue naevus in a 61-year-old male. Two biopsy specimens had been examined within 13 years, and revealed a common and cellular blue variant as a precursor. Locally invasive growth and regional lymph node swelling were present, but these alone could not confirm malignancy before evaluation of all clinical and histopathological features, as they are known to occur with benign cellular blue naevi. The recent literature and our case indicate that there is a malignant potential in every histological and clinical variant of blue naevus.