2011 年 50 巻 4 号 p. 242-243
We report invasive lobular carcinoma with apocrine differentiation in a 51-year-old woman. Despite fine-needle aspiration cytology four times, a definite diagnosis was difficult because cells with apocrine differentiation and unequivocal atypia were consistently found each time. These cells appeared as cellular clusters in which dyshesion was commonly observed. Scattered single cells with apocrine differentiation were numerous. These findings show the high discohesion of lobular carcinoma and the diagnosis was histologically confirmed in surgical specimens. Cellular apocrine cell clusters therefore suggest neoplastic lesions with apocrine differentiation and high discohesion suggests lobular carcinoma.