Glycogen-rich clear cell carcinoma of the breast: a case report.

Glycogen-rich clear cell carcinoma (GRCC) of the breast is a rare malignant breast tumor. We recently encountered a case of GRCC and report our imaging findings here. The patient was a 49-year-old woman with a mass in her right breast. Mammographic study showed no definite mass shadow because the breast was dense. No calcifications were identified. Ultrasonography disclosed a hypoechoic mass that had a diameter of 1.3 cm, partially irregular borders, heterogeneous internal echoes, and posterior acoustic enhancement, suggesting an invasive carcinoma. Histologic study of core needle biopsy specimens showed a solid proliferation of large clear carcinoma cells, suggestive of a ductal carcinoma. The carcinoma cells possessed clear cytoplasm larger than that typical of ductal carcinoma cells. Breast-conserving surgery was performed with axillary sentinel lymph node biopsy. Macroscopically, the tumor was a solid, white-yellow mass with fairly well defined margins. Histologic examination of the tumor showed a characteristic feature of GRCC: the tumor cells were positive for estrogen receptor but negative for progesterone receptor and Her 2, and the sentinel lymph node was histologically negative. The patient remains well and has had no clinical recurrence of the disease after 2.5 years of follow-up without radiotherapy or adjuvant therapy. Noteworthy is the usefulness of mammography and ultrasonography, which should be used as complementary imaging tools.