Fine needle aspiration cytology of invasive micropapillary carcinoma of the breast - Review of cases in a three-year period

OBJECTIVE: To describe the fine needle aspiration cytology findings of inva sive micropapillary carcinoma and correlate them with the histologic appear ance. STUDY DESIGN: We reviewed the cytologic features of three cases of pure inv asive micropapillary carcinoma in the files of Pamela Youde Nethersole East ern Hospital from 1998 through 2000, Immunohistochemical study for epitheli al membrane antigen was performed retrospectively on the cell block section s. Ultrastructural examination was also carried out on one of the cases. RESULTS: Two of the tumors were at pathologic stage II, and the remaining c ase was at stage II. Ipsilateral axillary lymph node metastases with simila r morphology were seen in two of them. Cytologically, the smears were of mo derate cellularity and composed of three-dimensional tumor cell balls, abor tive and sometimes branching papillae, angulated tumor cell clusters, morul es and occasional acini. Some of the tumor cell balls possessed scalloped b orders, Focally, the tumor morules clustered together and were separated fr om each other by small, slitlike spaces. A small number of isolated maligna nt cells was also present in the background. The cell block sections showed mainly dispersed acini of tumor cells. The "reverse polarity" highlighted in histologic sections by immunohistochemical study for epithelial membrane antigen was not consistently demonstrated in the cell block material. Ultr astructural examination confirmed the focal presence of surface microvilli on the periphery of the tumor cell morules. CONCLUSION. Invasive micropapillary carcinoma of the breast possesses some subtle but distinctive cytologic features. With the help of cell block morp hology and ancillary techniques, the preoperative suspicion of this rare su btype of ductal carcinoma, which carries a high propensity for lymphatic pe rmeation, is possible.