Malignant phyllodes tumor of the breast metastatic to the parotid gland diagnosed by fine needle aspiration biopsy. A case report.

BACKGROUND: Phyllodes tumor (cystosarcoma phyllodes) is a rare fibroepithelial neoplasm of the breast. Malignant phyllodes tumor is characterized by an infiltrative border and marked degree of hypercellular stromal overgrowth with > 5 mitoses per 10 high-power fields. Distant metastasis occurs in 10-20% of patients with malignant phyllodes tumor. The most common sites of distant metastases are the lungs, bone and abdominal viscera. Although theoretically any organ may have metastasis, the parotid gland has not been documented before in the English-language literature.

CASE: A 40-year-old, Caucasian woman with a history of malignant phyllodes tumor of the left breast presented with a mass on the right side of the parotid gland. Fine needle aspiration biopsy of the mass revealed abundant discohesive spindle cells showing moderate nuclear pleomorphism with occasional mitoses. No epithelial elements were seen. A diagnosis of malignant spindle cell tumor consistent with metastatic malignant phyllodes tumor was made. Histology confirmed the cytologic diagnosis.

CONCLUSION: Fine needle aspiration biopsy is accurate and efficient in conjunction with clinical information in the diagnosis of malignant phyllodes tumor of the breast metastatic to the parotid gland.