A case report of invasive ductal carcinoma of the breast with prominent sebaceous differentiation

Abstract

Background Sebaceous carcinoma of the breast is a rare entity, with only nine examples reported previously (WHO, 2012). Sebaceous carcinoma is defined as a breast carcinoma with prominent sebaceous differentiation in no less than 50% of cells (WHO, 2012). Limited data is available regarding the significance of sebaceous differentiation. Aim To present a case of diagnostic interest. Method and results We present a case of a 77-year-old woman with a self-detected left breast mass. After an initial core biopsy she underwent a mastectomy with sentinel lymph node biopsy. His-topathology confirmed an ER-positive/PR-positive/Her2-equiv-ocal invasive ductal carcinoma, with prominent sebaceous differentiation, and negative sentinel nodes. Discussion The amount of sebaceous differentiation falls just short of the greater than 50% required for diagnosis of sebaceous carcinoma. The differential diagnosis includes carcinoma with apocrine differentiation, lipid-rich carcinoma, and liposarcoma. A review of the available literature highlights the scarcity of knowledge of this rare entity. Very little is understood about the clinical course and prognosis of sebaceous carcinoma, and follow up data is limited. There is an association in the cases reported, with high grade tumours and high mitotic counts, and the predominant type of breast cancer associated is ductal. The two cases that have reported metastasis have been late in onset, and have occurred in sites which are not common for breast malignancies (scalp and skin). The significance of sebaceous differentiation is difficult to establish, and further research is warranted.