Megakaryocytes in fine-needle aspiration biopsy of breast

An unusual case in which megakaryocytes were found in fine needle aspirate of a breast lesion is reported. The megakaryocytes in the smears were initially mistaken to be malignant cells. However, the cell block sections available later showed normal bone marrow particles, indicating that an inadvertent puncture of a rib was the reason for the presence of megakaryocytes in the smears.