Whatever you choose to call these, it should be kept in mind that these tumors are the cutaneous marker for the Muir-Torre syndrome which includes carcinoma of the bowel. Multiple large lobules of tumor are confined to the dermis. These have relatively smooth concave borders and do not have a pattern of aggressive infiltration. Medium power view of a tumor lobule. High power view of above.
Sebaceous differentiation is seen centrally.
There is no peripheral palisading of nuclei. Mitoses are not seen, but they can be present in this type of tumor. Medium power view from another area. There is a ductal structure lined by squamous epithelium. This could be construed as a sebaceous duct or as follicular differentiation of the type that occurs at the junction of the sebaceous unit and the follicle.