To determine the value of cytology in the differential diagnosis of ductal versus lobular carcinoma of the breast.
In this study we examined 11 cytologic parameters in fine needle aspiration (FNA) cytology specimens from 52 patients who underwent surgery and had subsequent histologic diagnoses. Eighty-eight percent (46 cases) were infiltrating ductal carcinoma, and 12% (6 cases) were invasive lobular carcinoma.
Of the 11 cytologic parameters only chromatin pattern (P < .0001), nuclear size (P < .004) and overall cell size (P < .004) showed statistically significant differences between the two groups. Nuclear chromatin was coarsely granular only in cases of ductal carcinoma, while fine granularity could be seen in both ductal and lobular tumors. An automated morphometric system was used to determine the nuclear and overall cell size. The granularity of nuclear chromatin in ductal carcinoma cells did not correlate significantly with nuclear and overall cell size; therefore, they should be considered independent cytologic parameters.
The cytologic differential diagnosis of ductal versus lobular carcinoma is difficult; based on this study, the presence of coarsely granular chromatin, nuclear size > 44 microns2 and cell size > 82 microns2 are the only features diagnostic of ductal versus lobular carcinoma.