Image Description
Apocrine DCIS may extend into the lobules and mimic lobular carcinoma-in-situ (LCIS) as shown here. E-cadherin immunostain can be helpful in this setting. The neoplastic apocrine cells show diffuse membrane reactivity. In contrast, LCIS shows absent or fragmented staining.
Apocrine DCIS may involve an area of sclerosing adenosis which may simulate an invasive carcinoma. Myoepithelial markers may be helpful in working up such cases.
About the Disease
Apocrine morphology may be focally present in a variety of breast carcinomas, including ductal, lobular, mucinous, tubular, medullary and others. The term "apocrine carcinoma" is reserved for breast carcinomas in which majority of the tumor cells have apocrine morphology - consisting of abundant densely eosinophilic cytoplasm that may show granularity or vacuoles, enlarged nuclei and prominent nucleoli. They make up about 1% of all breast carcinomas. There are no major differences in the clinical features, mammographic presentation, or prognosis between apocrine and non-apocrine ductal carcinomas.Most cases of invasive apocrine carcinomas are negative for estrogen receptors (ER) and progesterone receptors (PR) and express androgen receptors (AR). About 50% of cases of pure apocrine carcinomas are HER2-negative. Gross cystic disease fluid protein 15 (GCDFP-15) - a marker of apocrine differentiation is expressed in majority of the cases, but it is not required to make the morphologic diagnosis of apocrine carcinoma.