Metaplastic carcinoma of the breast: fine-needle aspiration cytology of seven cases.

We describe the cytomorphology of seven cases of metaplastic carcinoma of the breast studied by fine-needle aspiration cytology and by histology. All seven cases contained foci of ductual adenocarcinoma. This finding was combined with heterologous mesenchymal elements in four cases, a spindle-cell pattern of growth in one case, and extensive squamous-cell metaplasia in two cases. Both carcinomatous and metaplastic components were present on smears in four cases (57%). Thus in three cases (43%), the diagnosis was not possible on smear material alone. Differential diagnostic considerations are discussed.