Scintimammographic findings of phyllodes tumor of the breast in a double-phase study with Tc-99m (V)DMSA and Tc-99m MIBI: a case report.

We present a case of phyllodes tumor of the breast in a 78-year-old woman evaluated with Tc-99m (V)DMSA and Tc-99m MIBI scintimammography, acquired in separate sessions (10 and 60 min post-injection). Tc-99m (V)DMSA was accumulated intensely within the mass [tumor to background ratio (T/B) >3], whereas Tc-99m MIBI had significantly lower uptake (T/B 1.9). Histology revealed a phyllodes tumor (maximum diameter 15 cm) and approximately three mitoses over 10 fields of view (FOV) x40, foci of epithelial hyperplasia and apocrine metaplasia. Stromal Ki-67 expression was 7%. The tumor was considered to be benign and the patient underwent mastectomy. One year later the patient presented with local malignant recurrence of the disease with over 15 mitoses per 10 FOV. Tc-99m (V)DMSA seems to have an advantage over Tc-99m MIBI in detecting mesenchymal tumors with unforeseen biological behavior and Ki-67 over-expression, such as phyllodes tumors, even with primary negative histological findings.