Spitz Nevus and Atypical Spitzoid Neoplasm
Spitz nevus (SN) and Spitzoid malignant melanoma (SMM) represent benign and malignant
counterparts at both ends of the spectrum of Spitzoid lesions. Atypical Spitzoid neoplasm
(ASN) is a poorly defined and characterized category of melanocytic tumors with histologic
features of both benign Spitz nevi and malignant melanomas. The group of ASN represents
a mixture of Spitz nevi with atypical features and Spitzoid melanomas. However, at the
current moment in time, histopathologists are not capable of differentiating between the 2
in some cases and are forced to place them in this ambiguous category, where the behavior
of these lesions cannot be predicted with certainty. Because this group encompasses both
benign and malignant lesions, and perhaps also a separate category of melanocytic tumors
that behave better than conventional melanomas, some of these neoplasms can metastasize
and kill patients, whereas others have no metastatic potential, and yet others might
only metastasize to regional lymph nodes. Although diagnostic accuracy has improved over
the years, many of these lesions remain controversial, and there is still poor interobserver
agreement in classifying problematic Spitzoid lesions among experienced dermatopathologists.
The objective of this review article is to summarize the most relevant information
about SN and ASNs. At this time histologic examination remains the golden standard for
diagnosing these melanocytic neoplasms. We therefore concentrate on the histopathologic,
clinical, and dermoscopic aspects of these lesions. We also review the most recent
advances in immunohistochemical and molecular diagnostics as well as discuss the
controversies and dilemma regarding whether to consider sentinel lymph node biopsy for
diagnostically ambiguous melanocytic neoplasms.
Semin Cutan Med Surg 29:165-173 © 2010 Elsevier Inc. All rights reserved.