Proliferative nodule resembling angiomatoid Spitz tumor with degenerative atypia arising within a giant congenital nevus

Proliferative nodules arising within congenital melanocytic nevi often present a diagnostic challenge given a close resemblance to melanoma. Several morphologic variants have been characterized. In difficult cases, ancillary molecular tests can be used to better exclude the possibility of malignant degeneration. Herein, we report a case of an unusual proliferative nodule with overlapping features of angiomatoid Spitz tumor and ancient melanocytic nevus, which demonstrated normal findings on both chromosomal microarray and a gene expression profiling assay.