[A case of low grade ductal carcinoma in situ of the breast with difficulties in making the preoperative diagnosis after detection by FDG-PET].

: A 56-year-old woman underwent FDG-PET screening, which demonstrated delayed-phase uptake in the lower part of the left breast. The findings of mammography, ultrasonography, MRI and cytological examination were compatible with ductal carcinoma in situ (DCIS), but core needle biopsy showed no evidence of malignancy. Therefore, partial resection of the left breast with sentinel lymph node biopsy was performed to make a definite diagnosis. Histological examination showed that this tumor was low grade DCIS. FDG-PET is a very useful examination to detect malignant diseases, but it is quite difficult to distinguish them from benign ones. It is suggested that delayed-phase uptake of FDG-PET is useful for diagnosis of DCIS.