In-situ and invasive carcinoma within a phyllodes tumor associated with lymph node metastases

BACKGROUND: Phyllodes tumors (cystosarcoma phyllodes) are uncommon lesions in the female breast. Rarely, the occurrence of carcinoma within a phyllodes tumor has been reported in the literature, but has never been associated with lymph node metastases. CASE PRESENTATION: A 26-year-old woman presented with a firm, mobile, non-tender mass in the left breast and palpable lymph nodes in the left axilla. The excised lesion appeared well circumscribed and lobulated, with variable fleshy and firm areas. Microscopic examination showed a circumscribed fibroepithelial lesion with a well developed leaf-like architecture, in keeping with a benign phyllodes tumor. The epithelial component showed extensive high grade ductal carcinoma in-situ (DCIS) and invasive carcinoma of no special type, located entirely within the phyllodes tumor. Subsequent axillary lymph node dissection revealed metastatic carcinoma in four lymph nodes. CONCLUSIONS: Although rare, phyllodes tumors may harbor DCIS and invasive carcinoma, with potential for lymph node metastasis.