Kirkham

 
"Most melanomas start as proliferations of atypical melanocytes at the base of the epidermis . . . As the tumour develops, the cells move in all directions. One of the most helpful features is the presence of individual melanocytes in the upper layers of the epidermis." (Fig. 9) Kirkham N. Biopsy pathology of the skin. London: Chapman and Hall Medical, 1991:112–3.

View Figure  		Fig. 9  Our diagnosis and comment: Melanoma in situ. This is not a "dysplastic naevus" because abnormal melanocytes disposed as solitary units and in tiny nests are present at all levels of the epidermis, including the spinous, granular, and cornified layers, a constellation of findings in this section that is diagnostic of melanoma.
 

Brief Critique

 
The findings said to be characteristic of melanomas are seen often in Spitz's nevi and, therefore, do not allow distinction between them.