Portion of E-DCIS Lesion Coexisting With Intraductal Papilloma of the Breast:—Immunochemistry of Synaptophysin for Diagnosis by Core Needle Biopsy—

Immunopositivity for neuroendocrine markers [NEs: synaptophysin (syn), chromogranin A (CGA), CD56, CD57, and neuron-spec  昀c enolase] is evidence of the presence of tumor cells with neuroendocrine cell differ‐ entiation in the breast. It has been reported that a certain type of breast cancer is immunopositi ve for NEs; such a breast cancer type has been named carcinoma with endocrine features or endocrine ductal carcinoma in situ (E-DCIS)．Here, we report a case of a patient in whom a portion of the E-DCIS lesion coexisted with intraduc‐ tal papilloma. A 38-year-old woman had an irregular hypoechoic lesion of the right breast on ultrasonographic examination, and core needle biopsy (CNB) of mass lesion was performed. Histopathologically, the CNB speci‐ men showed a 昀brovascu ar core with ductal hyperplasia, indicating that the lesion was most likely an intraduc‐ tal papilloma (IDP) with ductal h yperplasia. However, immunohistochemistry revealed that the CNB specimen from the right breast was focally positive for syn. We determined this lesion to be of the “indeterminate” type. An excisional biopsy of this right breast lesion was performed. This lesion was diagnosed as an E-DCIS lesion coexisting with intraductal papilloma. As such, the case presented suggests that immunopositivity for syn was a useful indicator for E-DCIS diagnosed by CNB.