One of the unusual features of this case is the presence of the clusters of hyperpigmented cells having epithelioid characteristics within the deep part of the lesion. Such clusters within the background of an ordinary nevus might prompt one to classify it as a combined nevus, a clonal nevus,  or (doubt) a minimal deviation melanoma. The choice would depend on the individual bias of the observer. A few isolated hyperpigmented epithelioid cells are also found in this lesion. The question remains open as to whether these cells represent a subclone (benign intralesional transformation) of the basic spindle/epithelioid cell nevus population or whether these represent regional variation in the phenotypic expression of the background cell population.

Scan power view. The lesion is asymmetrical. Collarette formation is present, indicating that the lesion  is expansile and not simply hamartomatous.

Composite low power view. The prominent, dilated deep blood vessels that have irregular outlines are of the type sometimes found at the junction of the reticular dermis and melanoma cells that expand the papillary dermis.

	High power view near the top of the above picture. Spindle cells are found in a slightly mucinous matrix. Keratinocyte hypertrophy and hyperplasia are present. Two eosinophilic bodies are present that could either be Kamino bodies or colloid bodies.
	High power view from a little deeper. Cytologic atypia is present but is within the range acceptable for a spindle/epithelioid cell nevus. A few of these cells are hyperpigmented, but they are scattered..
	High power view of clusters of hyperpigmented cells.
	High power view of deep part of the tumor. The 'nevus cells' (NC) are smaller than the superficial counterparts. This constitutes so-called maturation.

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