Atypical Spitz tumor arising on a congenital linear plaque-Type blue nevus: a case report with a review of the literature on plaque-Type blue nevus

The plaque-Type blue nevus (PTBN) is a rare variant of blue nevus, of which only a few reports are described. A nodular growth within a preexistent PTBN should always alert to the possibility of malignant transformation. The authors report the first case of an atypical Spitz tumor arising on a congenital linear PTBN in a 60-year-old woman. The diagnosis of "atypical Spitz tumor" is here used to describe a microscopic "gray zone" in which it is not possible to differentiate with adequate certainty between a Spitz nevus and a spitzoid melanoma. This report adds to and summarizes the small body of literature describing PTBN and discusses diagnosticand clinical implications.