Multiple agminated Spitz nevi arising on a café au lait macule: review of the literature with contribution of another case.

The majority of Spitz nevi are acquired solitary lesions. Multiple Spitz nevi are rare and may develop on hyperpigmented skin. We report a 16-year-old girl with multiple Spitz nevi arranged on a café au lait macule. Immunohistochemistry showed positivity for S-100 and HMB-45. Of interest, expression of Polo-like kinase (PLK), a novel proliferation marker that recently proved to be positive in up to 98% of malignant melanoma cells, showed positivity in 40% of the nevus cells. The clinical development of multiple Spitz nevi is not yet clear, as they are preferentially excised. Reviewing 70 cases in the literature we found that multiple agminated Spitz nevi occur more frequently than reported previously. In about one-third of these cases Spitz nevi arose on congenitally hyperpigmented skin.