Metastatic hepatocellular carcinoma of the breast, simulating gynecomastia: diagnosis by fine-needle aspiration biopsy.

Hepatocellular carcinoma (HCC) may uncommonly present with distant metastasis in the absence of a documented neoplasm in the liver. The authors herein describe the case of a 60-year-old man with cirrhosis who developed unilateral enlargement of the breast and a subareolar mass. This problem was clinically thought to represent gynecomastia, but a mammary fine-needle aspiration biopsy demonstrated a malignant epithelial neoplasm composed of large granular amphophilic cells. Bile pigment was visualized in the tumor on aspirate smears and cell block preparations; immunostains showed reactivity for cytokeratin and alpha-fetoprotein, but there was no positivity for epithelial membrane antigen, gross cystic disease fluid protein-15, vimentin, estrogen receptors, progesterone receptors, or S100 protein. These results indicated a diagnosis of metastatic HCC, which was subsequently confirmed by computed tomography of the abdomen.