Isoechoic axillary lymph node metastases of mucinous carcinoma of the breast: a case report.

We report a case of isoechoic axillary lymph node metastasis of mucinous carcinoma (so-called pure mucinous carcinoma) of the breast. A 47-year-old premenopausal woman was referred to our hospital with a 2 years history of mass and distortion of her left breast and with recent worsening of her symptoms. Ultrasonography demonstrated a well-circumscribed mass, about 5 cm in diameter, which was isoechoic compared to the surrounding fat tissue. Distal enhancement was also recognized. A left axillary ultrasonographic scan demonstrated four nodules, which were indistinct because of their isoechogenicity compared to the surrounding tissue. Based on a preoperative diagnosis of mucinous carcinoma of the left breast with left axillary lymph nodes metastases, left mastectomy and left axillary nodal dissection were performed. Mucinous carcinoma with axillary lymph node metastases was diagnosed histologically. The lymph node metastases showed histological findings identical to those of the primary tumor, which was considered to be the reason for their isoechogenicity. Although lymph node metastasis of mucinous carcinoma of the breast is rare, ultrasonographers should perform careful scanning when the primary breast mass is suspicious for mucinous carcinoma, because lymph node metastases of mucinous carcinoma can be more indistinct and difficult to detect than those of other types of breast cancer.