2004 年 43 巻 3 号 p. 233-234
We report a case of breast carcinoma with osteoclast-like giant cells (OCGCs) in a 34 year-old woman. The smear obtained by fine needle aspiration showed a mixture of atypical epithelial cells and many multinucleated giant cells. These epithelialcells were revealed as cohesive cellular clusters and cells showed mild-moderate atypia. The multinucleated giant cells had vesicular nuclei with prominent nucleoli. From the histological find-ings. the tumor was identified as an invasive ductal carcinoma showing a papillotubular pattern with many OCGCs in the stroma. Immunohistochemical examination showed that the OCGCs were positive for CD68 but negative for keratin. These results suggest the OCGCs are derived from histiocytic cells.