Routine light microscopy supplemented with immunohistochemistry in cases of metastatic or spindle cell melanoma are standards of care for the diagnosis and staging of melanoma. Not all melanocytic tumors can be confidently classified as melanoma or benign nevus by histology, however. In addition, tumor thickness and ulceration, the current American Joint Classification on Cancer prognosticators for primary cutaneous (stages I and II) melanoma used in clinical practice, do not perfectly predict an individual's clinical course. Recent advances in molecular techniques and bioinformatics mandate testing and use of novel methods for the detection, diagnosis, and classification of melanocytic tumors that can accurately predict tumor behavior and help in selecting the most optimal and individualized therapy. © 2009 Elsevier Inc. All rights reserved.