[Giant-cell reaction in the breast after fine-needle aspiration]

We report two cases in which fine needle aspiration (FNA) in the breast generated changes histologically mimicking malignant lesions. In both cases a population of giant cells was present; the cells were osteoclast-like in the first case and 'atypical' multinucleated stromal giant cells in the second. The underlying lesion was pseudoangiomatous stromal hyperplasia (PASH) in both cases. The reactive nature was confirmed by retracing the needle tract and by the uneventful follow-up of 7 or 2 years, respectively. We propose that giant cell reaction be included in the list of FNA-generated changes.