McCarthy et al.

 
"In particular, the irregular arrangement of variably sized nests of melanocytes in association with solitary atypical melanocytes well above the dermo-epidermal junction distinguishes in situ melanoma from acquired banal junctional naevi, and junctional types of dysplastic and Spitz naevi. Thus early melanoma can be diagnosed histologically when it is small, flat, and curable." McCarthy WH et al. Can early melanoma be diagnosed? In: Cascinelli N, Santinami M, Veronesi U. Cutaneous melanoma biology and management. Italy: Masson, 1990:120–1.
 

Brief Critique

 
The findings cited do not distinguish melanoma in situ from many examples of Spitz's nevus confined to epidermal and adnexal epithelium.