IS Case 108: Phyllodes Tumor
Imaging Sciences URMC 2008
Publication Date: 2009-05-20
Patient is a 43-year-old woman who noted a lump in her left breast for 1 year.
Cystosarcoma phyllodes tumors account for approximately 0.3% of all breast tumors and usually occur as solitary, unilateral breast mass which may enlarge rapidly. In addition, the average age of the patient with phyllodes tumors is approximately 45 years. Up to 25% of lesions are malignant which occur in slightly older patients. The tumor are thought to be hormonally responsive. Coexisting fibroadenomas reported in 20%-40% of patients.
In general, phyllodes tumors may be classified as benign, borderline, or malignant; most phyllodes tumors are benign. Benign phyllodes tumors characteristically have smooth, noninfiltrating borders with hypocellular stromal components, minimal nuclear atypia, and low mitotic activity. Factors suggesting malignancy include increased mitotic activity, pronounced proliferation of stromal components relative to glandular structures, cytologic atypia, and invasive peripheral growth with infiltration into adjacent tissues. Approximately 5–25% of phyllodes tumors are described as malignant. Fewer than 20% of the malignant tumors metastasize. When metastatic disease occurs, the metastases usually spread hematogenously to the lungs, pleura, or bone.
Mammographically, the masses are usually dense, oval or round, noncalcified, smoothly marginated masses but rarely have calcifications. Approximately 20% of cases are detected as nonpalpable mass on screening mammogram and patients presenting with palpable lesion give a history of sudden rapid growth in a preexistent mass. Lesions larger than 3 cm in size are more likely to be malignant.
MRI shows mass with circumscribed margins; cystic changes may be present. Continuous uptake or plateau type kinetic curves; some may be characterized by rapid initial enhancement and washout of contrast. Rim enhancement may be seen.
Wide local excision is critical to minimize likelihood of local recurrence; in some patients this may require a mastectomy. Higher recurrence rates seen following incomplete excision and in the tumors with invasive borders and secondary nodules at the periphery of the main lesion.
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