Polypoid Spitz nevus: two cases evaluated with genetic technique, prolonged follow up, and sentinel lymph node biopsy.

Polypoid Spitz nevus represents a spitzoid melanocytic neoplasm that frequently has worrying and challenging histopathological details. Distinction from polypoid melanoma may not be straightforward. Two cases of polypoid Spitz nevus with striking histopathological features were studied. One case had prolonged follow up (Case 1) and one patient had undergone sentinel lymph node biopsy (Case 2), and fluorescence in situ hybridization (FISH) analysis was also completed (both cases). Follow up and genetic analysis of three control cases of polypoid melanoma is also presented. Our clinical and genetic results suggest that both the polypoid Spitz nevi were benign. The patients are alive with no evidence of disease. FISH analysis did not show abnormalities with probes tested. This is in sharp contrast with the control cases of polypoid melanoma, wherein genomic alterations were detectable. Our data indicate that the two polypoid lesions presented here are most probably benign, despite their worrying histopathological features. More cases with long-term follow up and greater numbers of DNA probes are necessary to extend this conclusion to other ambiguous melanocytic tumors.