Mammary carcinoma with multinucleated osteoclast-like giant cells (OCGCs), an uncommon neoplasm, features giant cells morphologically resembling osteoclasts. A 76-year-old woman noticing a left breast cystic mass was found in fine-needle aspiration cytology (FNAC) to have many atypical epithelial cells with OCGCs. Immunohistochemical studies indicated that OCGCs were of histiocytic origin. FNAC specimens make it easy to observe OCGCs, so FNAC becomes useful in diagnosing breast carcinomas with OCGCs.
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.