Fine-needle aspiration cytology of breast carcinoma with endocrine differentiation

The value of fine-needle aspiration (FNA) in atypical proliferative to in situ to low grade invasive breast lesions remains limited due to the overlapping cytologic features of these entities. In the current study the authors review the FNA cytology of endocrine carcinoma and identify common cytologic features that allow for the diagnosis of this uncommon, low grade subtype of mammary malignancy.

The histopathology files from the medical practices of both authors were searched between January 1996 and May 1999 and yielded six cases of endocrine carcinoma. The clinical history and all previous FNA smears were reviewed.

All six patients were elderly women (mean age of 72 years). Four patients presented with breast masses, one patient presented with nipple discharge, and one patient presented with both a breast mass and nipple discharge. All six surgical specimens showed endocrine ductal carcinoma in situ (E-DCIS), with four specimens showing invasive endocrine carcinoma, two of which were labeled as mucinous carcinoma. All invasive components showed the same histomorphologic and immunohistochemical profiles as the in situ components. Cytology demonstrated common features of the cellular smears with clusters and single, monomorphic plasmacytoid tumor cells that possessed moderate amounts of eosinophilic, granular cytoplasm and eccentric nuclei with fine chromatin and inconspicuous nucleoli. In four cases, additional fragments of fine and elaborate papillary fronds also were present.

The cytologic smear diagnosis of endocrine carcinoma is assisted by the presence of plasmacytoid tumor cells and arborizing papillary fronds.