Fine-needle aspiration cytopathology--an accurate diagnostic modality in mammary carcinoma with osteoclast-like giant cells: a study of 8 consecutive cases.

Background: Invasive ductal carcinoma with osteoclast-like giant cells (OGCs) is a very rare breast tumor the main characteristic of which is the presence of multinucleated cells of histiocytic nature.

Methods: The authors report a study of 8 consecutive cases of fine-needle aspiration cytopathology (FNAC) of breast nodules in which OGCs and malignant epithelial cells were associated and diagnosed as mammary carcinoma with OGCs. These cases were selected over a period of 5 years from more than 6000 patients who were examined during a weekly, single-day, multidisciplinary breast clinic. The corresponding biopsies and surgical specimens were examined histologically in an immunohistochemical study using a histiocytic marker (cluster of differentiation 68 [CD68]).

Results: Conventional histologic analysis made it possible to diagnose 5 of the 8 cases as mammary carcinoma with OGCs; whereas, in the other 3 cases, OGCs were not detected without the help of immunohistochemistry.

Conclusions: FNAC appeared to be a very efficient way to diagnose breast carcinoma with OGCs, because it detected forms with only a few OGCs that usually are not observed at histologic diagnosis. Consequently, the current results indicated that mammary carcinoma with OGCs may be more frequent than reported previously.