Recurrence of invasive micropapillary carcinoma of the breast with different ultrasound features according to lesion site: case report.

Invasive micropapillary carcinoma (IMPC) of the breast is a distinct variant of breast cancer. Extensive lymphatic penetration, lymph node metastasis, and local recurrence are seen at a relatively high frequency. On ultrasound (US) findings, IMPC has been reported to be an irregular or lobulated mass with hypoechoic internal areas, but as yet there is no consensus regarding typical findings. A 52-year-old female noticed a mass less than 3 cm in diameter in her left upper breast. US findings indicated an irregularly shaped, hypoechoic tumor with indistinct margins. The diagnosis according to fine-needle aspiration cytology was invasive ductal carcinoma. She underwent lymph node dissection with mastectomy of the left breast. Histological examination revealed mixed-type IMPC. Three years and three months after surgery, IMPC recurred under the skin of the surgical scar. US findings indicated a hyperechoic tumor in this region. Eight months after further surgery, a tumor in the anterior chest wall was observed. US findings indicated an oval hypoechoic tumor with posterior acoustic enhancement. US findings differed between primary and recurrent IMPC because of differences in the occupancy and distribution of IMPC. We describe here a comparison between US and histological findings, as well as differences in IMPC between primary, secondary and tertiary sites.