Breast inflammation is a difficult clinical problem as it can result from a variety of causes: specific or non-specific infectious mastitis, which may or may not be complicated, primary or secondary inflammatory mastitis or inflammatory cancer. The main objective of radiology is to eliminate an inflammatory cancer. Other objectives are to characterise an inflammatory condition (where the clinical context is valuable in guiding diagnosis but which often requires a micro- or macrobiopsy) or to obtain a microorganism in cases of complicated infectious mastitis (a diagnostic procedure but also comprising the first stage of treatment). Whether for bacteriological or histological purposes, percutaneous samples therefore play a large part in the diagnostic procedure, other than in the clinical context of pregnancy where mastitis is more easily diagnosed because of its frequency. The guidance method is usually ultrasound, and the needle chosen will depend on the radiological or ultrasound signal: puncture with an 18G needle will be used for a bacteriological sample, microbiopsy of a mass or lymph nodes, or macrobiopsy in the case of microcalcifications.