Polypoid Spitz naevus: the benign counterpart of polypoid malignant melanoma

Polypoid malignant melanoma is a peculiar morphological variant of melanoma with a distinct exophytic pattern of growth. This form of melanoma is usua lly very thick and the prognosis is accordingly poor. We present here a pre viously undescribed form of Spitz naevus which had a similar polypoid exoph ytic silhouette and marked cytological atypia. Despite these close morpholo gical similarities, polypoid Spitz naevus evolves in a completely benign ma nner, Morphologically, polypoid Spitz naevus can be distinguished from poly poid melanoma by the absence of mitoses and by the prominent stromal reacti on throughout the lesion.