Fine-needle aspiration cytology of lobular carcinoma in situ

Fine-needle aspiration cytology (FNAC) plays a key role in the preoperative diagnosis of breast carcinoma but is less reliable in the diagnosis of in situ lesions. The objective of the present study was to investigate the cytological features of lobular carcinoma in situ (LCIS), regarding which little data is available to date. Cytological features of FNAC of the breast from 21 patients with histology-proven LCIS were described and compared with surgical specimens. Aspirates from 8/21 cases had cell groups diagnostic for or compatible with LCIS. Aspirates from an additional two cases demonstrated hypercellular, dissociated, and more pleomorphic tumor cells, which were originally diagnosed as invasive lobular carcinoma (ILC). The remaining 11 aspirates were diagnosed as benign or nondiagnostic. FNAC from the eight diagnostic specimens were characterized by loosely cohesive cell groups composed of uniform cells with occasional intracytoplasmic lumina, slightly irregular and eccentric nuclei. We conclude that the main difficulty in diagnosing LCIS by FNAC is sampling rather than recognition of the lesions. However, one should be aware of the cytological features of LCIS in order to reach a correct diagnosis. There are no reliable cytological criteria that help in differentiating pleomorphic and dissociated LCIS from ILC.