Fine-needle aspiration cytology of pleomorphic lobular carcinoma of the breast. Comparison with the classic type.

BACKGROUND. The pleomorphic variant of invasive lobular carcinoma shares the typical infiltrating histologic pattern of classic invasive lobular carcinoma, but differs from it in its nuclear pleomorphism and aggressive behavior. The purpose of this study was to describe the fine-needle aspiration (FNA) cytologic findings of the pleomorphic variant of lobular carcinoma and to compare them with those of classic lobular carcinoma. METHODS. Among 405 breast FNA performed in 1995, 7 examples of classic infiltrating lobular carcinoma and 4 cases of this neoplasm's pleomorphic variant were identified; all were histologically confirmed. The FNA from three of the four pleomorphic variant cases and from two of the seven classic lobular carcinoma cases were diagnostic of malignancy; these were evaluated for a variety of cytologic criteria, which were graded from 0 to 3. RESULTS. Although exhibiting many cytologic features in common with the classic type, such as indian files and cytoplasmic vacuoles, the FNA of the pleomorphic variant differed in their tendency to yield greater cellularity, larger cell size, and, particularly, more pleomorphic nuclei. CONCLUSIONS. The FNA cytologic findings of the pleomorphic variant of lobular carcinoma are characteristically hybrid between those of classic lobular carcinoma and ductal carcinoma.