Natural evolution of Spitz nevi.

Background: The natural evolution of melanocytic nevi is a complex, multifactorial process that can be studied by monitoring nevi on a long-term basis.

Methods: To assess the evolution pathway of Spitz nevi, lesions with clinical and dermoscopic features suggestive of Spitz nevi were monitored and baseline and follow-up images compared.

Results: Sixty-four patients (mean age 10.4 years) with lesions suggestive of Spitz nevi were included. Lesions were monitored for a mean follow-up period of 25 months. Upon side-by-side evaluation of baseline and follow-up images, 51 (79.7%) lesions showed an involution pattern and 13 (20.3%) lesions showed a growing or stable pattern. No significant differences were found between growing and involving lesions in terms of patient age and sex and the location and palpability of lesions. The great majority of growing lesions were pigmented or partially pigmented (92.3%), whereas 47.1% of lesions in involution were amelanotic (p = 0.005).

Conclusion: In this series of lesions clinically and dermoscopically diagnosed as Spitz nevi, spontaneous involution seems to be the most common biologic behavior.