A rare case of adenoid cystic carcinoma of the breast detected by (18)F-FDG PET/CT.

A 51-year-old female patient underwent 18F-FDG PET/CT searching for the cause of a fever of unknown origin. Before 18F-FDG injection, the patient had fasted for at least 6 h; at the time of the radiopharmaceutical injection the glucose blood levels corresponded to 96 mg/dL. Images were acquired 1 h after i.v. injection of 280 MBq of 18F-FDG. 18F-FDG PET/CT showed an area of increased radiopharmaceutical uptake corresponding to a 2.5 cm lesion in the left breast (Fig. 1A–C) with a maximum standardized uptake value (SUVmax) of 3.4. No other areas of abnormal 18F-FDG uptake were detected in the rest of the body. Based on this 18F-FDG PET/CT finding the patient underwent mammography and ultrasonography of the breast which showed a 2.5 cm irregular nodule in the left breast. Therefore an excisional biopsy of the breast nodule was performed. At hematoxylin and eosin stain the breast nodule was composed of basaloid cells arranged into a cribriform pattern with small, angulated, and hyperchromatic nuclei and scant cytoplasm (Fig. 1D). This tumor did not express estrogen receptor alpha, progesterone receptor, or human epidermal growth factor receptor 2 (“triple-negative” feature). A final diagnosis of adenoid cystic carcinoma (ACC) of the left breast was