Sarcoidosis Mimicking Metastatic Breast Cancer on FDG PET/CT

A 32-year-old woman with breast cancer underwent FDG PET/CT. In addition to the primary left breast lesion [Picture, arrowhead, SUVmax: 23.6, a: Maximum Intensity Projection (MIP) PET], multiple left axillary lymph node metastases were detected (Picture, short arrows, SUVmax: 21.4-32.6, a: MIP). Additionally, multiple hypermetabolic mediastinal and bilateral hilar nodes were noted in a "butterfly" distribution pattern (Picture, long arrows, SUVmax: 10.4-12.5, a: MIP). A biopsy of a left axillary lymph node (Picture, short arrows, b: PET, c: CT, d: fused PET/CT) showed metastatic infiltrating ductal carcinoma [Picture, short arrows, e: Hematoxylin and Eosin (H&E) staining, 200 magnification], while that of a peribronchial lymph node (Picture, long arrows, b: PET, c: CT, d: fused PET/CT) revealed well-formed non-caseating granuloma (Picture, long arrows, f: H&E staining, 200 magnification) histologically consistent with a diagnosis of sarcoidosis.