Breast carcinoma arising in cystosarcoma phyllodes: report of a case with a review of the literature.

An extremely rare case of coexistent carcinoma arising in a cystosarcoma phyllodes of the breast is reported. A 41-year-old Japanese woman was referred with a lump in the right breast. A tumor measuring 5.6 X 3.6 X 3.2 cm was removed by local excision. Histological examination revealed foci of papillo-tubular carcinoma within the benign cystosarcoma phyllodes. Radical mastectomy was performed and the axillary lymph nodes showed no metastasis. While 22 cases of coexistent carcinoma and cystosarcoma phyllodes in the same breast have been reported, in only nine of those cases, the carcinomas including this case have developed within the cystosarcoma phyllodes.