[Papular plaque-type blue nevus].

INTRODUCTION: Rare clinical presentations of common diseases are sometimes worth of publication. Their knowledge may help to avoid diagnostic mistakes. OBSERVATION: In a 6 year-old boy a cluster of pigmented blue papules spread slowly on the inner aspect of his left foot. The extension over years and the linear arrangement of the plantar papules suggested the possibility of a malignant melanoma. However the histological examination of 2 biopsies showed the structure of a common blue nevus. DISCUSSION: About a dozen cases of such papular plaque-type blue nevi have been described. Histologically they disclose the same cellular types than common blue nevi. In all the reported cases the course was benign; in our case the decision of abstention was sustained by this information.