Fat Necrosis of the Breast Following Folinic Acid Extravasation.

Case Report: We report here on a 58-year-old patient with abnormal findings in the left breast on screening mammography (October 2012). In May 2008 the patient was diagnosed with rectal cancer, subsequently treated by surgical resection followed by radiochemotherapy. In September 2011 the patient was diagnosed with peritoneal cancer. Extravasation of folinic acid occurred during palliative chemotherapy, which was delivered through a surgically implanted port, placed prepectorally on the left side. The patient had not previously undergone breast surgery. The abnormal finding in the left breast was located at the 1-2 o'clock position. The mammogram showed extensive hyperdense nodules with predominantly round, fine granular calcifications. On sonography, the findings presented as a hypoechogenic, inhomogenous, partially diffuse, partly solid, partly cystic mass with individual calcifications and reduced echogenicity in the dorsal aspect. Strong densification of the left breast was found at the corresponding position on palpation. On computed tomography (CT) done during follow-up for rectal cancer, new streaky/pitted densifications were noted in the left breast. Based on the patient's previous history and the results of the breast diagnostics a diagnosis of extensive fat necrosis after folinic acid extravasation was made. No further measures were taken. The patient will continue to be screened using mammography. Conclusion: A good knowledge of the mammographic and sonographic features of fat necrosis can reduce the number of unnecessary biopsies. Careful consideration of the patient's prior medical history is very important in breast diagnostics and may often be decisive for the correct diagnosis.