Cytological findings of invasive micropapillary carcinoma of the breast

Objective: We studied cytological features of invasive micropapillary carcinoma (IMPC) of the breast, which may show a poor prognosis. Study Design: Fine-needle aspiration cytology smears from 10 IMPC cases-3 pure and 7 mixed-were reviewed. Background, amount of carcinoma cells, cohesiveness of tumor cell nests, architecture and size of cell clusters, and nuclear features of individual cell were evaluated. Results: Characteristic cytological features of IMPC were: 1) clear background, 2) abundant carcinoma cells as small to middle clusters of sheet-like or papillary contour, small clusters of 10 to 20 cells, or as individual cells, 3) smooth surface of papillary clusters with cytoplasmic contour, and 4) small, round to oval nuclei with slight anisonucleosis, and increased nuclear chromatin. Conclusion: These cytological features enable us to presume IMPC and are information important for the patient's prognosis.