Spitz Nevi, Atypical Spitzoid Neoplasms, and Spitzoid Melanoma.

Spitz nevi and melanoma represent benign and malignant counterparts commonly coupled in the same differential diagnosis. The precise distinction between the two entities remains an ongoing challenge in dermatopathology and surgical pathology. In past years, considerable work has been devoted to the assembly of criteria to permit exact diagnosis. Although diagnostic accuracy has improved, many lesions remain challenging to classify based solely upon conventional microscopic criteria. In this article, the clinical and histopathological attributes of Spitz nevi and spitzoid melanoma are reviewed. Lesions that cannot be definitively classified based solely upon conventional microscopic criteria are referred to as atypical spitzoid neoplasms, which the authors view as a provisional diagnostic category rather than as a formal disease entity. Molecular assessment by way of comparative genomic hybridization or fluorescence in situ hybridization is increasingly used to facilitate assessment of this challenging differential and is especially germane to the evaluation of ambiguous lesions.