Case Number : Case 2286 - 19 March 2019 Posted By: Uma Sundram

Nodular growth with rounded but definetely infiltrative margins, made up of atypical sebocytes in different stages of maturation----->>sebaceous carcinoma.

nodular Sebaceous gland carcinoma, however cystic spaces with eosinophilic fluid I have not seen in SGC, 

I will go with Sebaceous carcinoma

Or sebaceoma? Muir Torre syndrome?

Looks like a small sebaceous adenoma (rather then obvious carcinoma). It's clearly in situ in either case. I'd run p53 for interest. MTS unlikely with solitary sebaceous lesion at this site.

There is a stromal desmplasia in fig2 and fig3, around the pseudo-circumscribed margin, so I think this a clue to neoplastic invasion of muscle layer.

Difficult lesion to classify. To me it is a sebaceoma or a sebaceous adenoma (depends on whether you think the basaloid cells are >50% or not) because of the lack of infiltrative growth pattern. To me the degree of cytologic atypia is definitely there but not severe.

This is a difficult case, as evidenced by the numerous comments with varying opinions. We did not pull the trigger on carcinoma but were concerned about the lesion (sebaceous neoplasm with atypical features). It was completely excised. All MSI proteins were retained.

Thank you again, colleagues, for your wonderful and thoughtful comments.

sebaceoma. nice case!