Malignant phyllodes tumor metastatic to the lung with osteogenic differentiation diagnosed on fine needle aspiration biopsy. A case report

BACKGROUND: Osteosarcomatous differentiation in malignant phyllodes tumors is rare. No cases of either primary or metastatic lesions were identified in the literature that were initially diagnosed on fine needle aspiration biopsy. CASE: Cytologic and histologic findings of a metastatic malignant phyllodes tumor with osteosarcomatous differentiation in a 63-year-old woman are presented. This case was diagnosed initially on fine needle aspiration biopsy and confirmed with histologic examination of the pulmonary lesion. CONCLUSION: Although rare, the differential diagnosis of metastatic phyllodes tumor should be considered in the appropriate clinical setting when examining a pleomorphic spindle cell tumor with heterologous elements on fine needle aspiration biopsy.