Intracystic papillary carcinoma of the female breast with secretory activity: the significance of aspiration cytology as diagnostic procedure.

We report the case of an intracystic papillary carcinoma of the breast in an elderly woman. Gross and microscopic observations support the contention that intracystic fluid is partly a result of secretory activity by the neoplastic epithelial cells and that, intracystic hemorrhage, which may contribute to it, is a secondary event complicating the primary process. Cytology of the aspirated fluid was negative for malignant cells. It is concluded that in the case of large cystic breast lesions, aspiration cytology may not be helpful in establishing the malignant nature of the lesion and that a negative cytology should be interpreted with caution, always taking under consideration the clinical picture of the disease. A concomitant adenocarcinoma was also present in the opposite breast, the second case reported in the literature.