Microglandular adenosis of the breast is a benign proliferative lesion, and is a rare subtype of adenosis. The pathologic findings and clinical symptoms can mimic those of breast cancer. Microglandular adenosis has been frequently associated with invasive carcinoma and in situ carcinoma of the breast. Many reports have described a spectrum of the lesions, ranging from microglandular adenosis to cancer arising from microglandular adenosis. However, most of them have focused on the pathology, and there are a few cases that report imaging findings. In the present case, we report the imaging and pathologic findings of a ductal carcinoma in situ arising in microglandular adenosis. A 57-year-old woman detected a palpable mass in her left breast. Mammogram showed an ill-defined irregular isodense mass, and sonogram showed hyperechoic irregular mass with indistinct margin. The patient underwent breast conserving surgery and adjuvant radiotherapy.