Eruptive Spitz nevus, a striking example of benign metastasis.

Metastasis is generally considered a characteristic of malignant tumors. Herein, we describe a patient with more than one hundred discrete Spitz nevi scattered all over her skin. Molecular analysis from three of the lesions identified a ROS1 fusion oncogene with identical genomic breakpoints, indicating that the nevi arose from a single transformed melanocyte and then disseminated throughout the integument.