A 52-year-old woman was found to have a lung mass and bilateral breast lesions on computed tomography (CT). Subsequent positron emission tomography/CT demonstrated marked uptake in the lung mass and mild uptake within the breast lesions. A diagnostic mammogram and targeted ultrasound were performed to exclude primary breast malignancy or metastases from presumed pulmonary malignancy. A pertinent history of recent intravenous drug use with heroin injection into bilateral breasts, together with imaging features, facilitated diagnosis of fat necrosis. Fat necrosis is a common diagnosis in breast imaging and may be an incidental finding on positron emission tomography/CT in the oncologic setting. The presence of fat along with suggestive clinical history can lead to the diagnosis and appropriate assignment of either benign, breast imaging-reporting and data system (BI-RADS) 2, or probably benign, BI-RADS 3, category with short interval follow-up. Appropriate work-up of incidental fluorodeoxyglucose-avid breast masses with diagnostic mammogram ± ultrasound is warranted to avoid incorrect interpretation as neoplastic processes.
Keywords: Breast; Breast lump; FDG PET-CT; Fat necrosis; Intravenous drug use.