sebaceoma

SEBACEOMA (SEBACEOUS ADENOMA, EPITHELIOMA, OR YOUR PREFERENCE)

The terminology regarding indolent tumors having sebaceous differentiation can be confusing in that the term sebaceous epithelioma has been used not only for the indolent tumors but also for more aggressive ones that would be better designated as basal cell carcinoma with sebaceous differentiation. The term sebaceoma
is used by some to designate tumors that are slightly less differentiated than adenoid sebaceous hyperplasia on one end of the spectrum and more primitive tumors (over 50% basaloid cells) that do not have the profiles of basal cell carcinoma on the other end of the spectrum. An alternate system of classification would designate all benign tumors within this spectrum as sebaceous adenomas with adenoid sebaceous hyperplasia being equivalent to well-differentiated sebaceous adenoma and sebaceoma equivalent to poorly differentiated sebaceous adenomas. Sebaceous adenomas, under this system of classification, would be designated as moderately-differentiated sebaceous adenomas. Whatever you choose to call these, it should be kept in mind that these tumors, with the exception of sebaceous hyperplasia, are the cutaneous marker for the Muir-Torre syndrome which includes carcinoma of the bowel.

Solitary lesion from the face of an adult female:

Scan power view. Multiple large lobules of tumor are confined to the dermis. These have relatively smooth convex borders and do not have a pattern of aggressive infiltration.

Medium power view of a tumor lobule. Although over 50% of the cells are 'basaloid', other cytologic and architectural features of basal cell carcinoma are not seen.

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.

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	Scan power view. Multiple large lobules of tumor are confined to the dermis. These have relatively smooth convex borders and do not have a pattern of aggressive infiltration.
	Medium power view of a tumor lobule. Although over 50% of the cells are 'basaloid', other cytologic and architectural features of basal cell carcinoma are not seen.
	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.