A pictorial review: multimodality imaging of benign and suspicious features of fat necrosis in the breast

Abstract

Fat necrosis of the breast is a well-described benign entity that can result in unnecessary biopsy of breast lesions. The pathogenesis of fat necrosis is a non-suppurative inflammatory process of adipose tissue, which may be seen after trauma, surgery, biopsy, post-breast reconstruction, post-fat grafting, post-radiotherapy, infection, and duct ectasia, among other conditions. Clinically, these patients may be asymptomatic or may present with a palpable lump, skin tethering, induration, and occasionally axillary lymphadenopathy. Depending on the time at which diagnostic imaging is performed, fat necrosis can have highly variable appearances on different modalities as it evolves. This is directly related to whether inflammation or fibrosis is predominating within the lesion, and correlation with clinical history is paramount in evaluating these patients. This review aims to analyze benign and suspicious imaging features of fat necrosis confirmed by tissue sampling. Knowledge of both benign and malignant-appearing features of fat necrosis on conventional modalities such as mammography and ultrasound, as well as newer applications including digital breast tomosynthesis, PET/CT, and MRI, should help the radiologist minimize the number of unnecessary biopsies.

Cellular Spindled Histiocytic Pseudotumor: A Benign Mimic of Spindle Cell Neoplasia of the Breast

“…1,2 Less common causes include post-breast reconstruction, post-fat grafting, infection, duct ectasia, and rarely autoimmune disease. 3 This process often presents as a palpable mass identified via self or clinical examination with or without a prior history of antecedent trauma to the affected area. It can also present with other, often concerning, findings such as nipple retraction and ipsilateral axillary lymphadenopathy.…”

“…1 Mammographically, mammary fat necrosis can manifest in a variety of patterns, most commonly as oil cysts with dystrophic (''eggshell'') calcifications. 3 However, it can also present as a spiculated area of increased opacity with associated distortion, closely mimicking invasive mammary carcinoma. Ultrasonographically, fat necrosis commonly presents as increased echogenicity of the subcutaneous tissues, supporting benignity based on the very low percentage of hyperechoic cancers.…”

“…4 Magnetic resonance imaging (MRI) can be a useful adjunct when fat suppression sequences are used in order to distinguish fatty lesions from enhancing lesions on T1-weighted MRI. 3,4 Overall, the constellation of sometimes worrisome clinical and radiographic features often necessitates core biopsy.…”

Natural Course of Fat Necrosis After Breast Reconstruction: A 10-Year Follow-Up Study

“…Fat necrosis may be suggested with typical imaging features (calci ed nodule in mammography and ultrasonography, peripheral site of the reconstructed ap, and poor vascular supply) (13). However, when the shape of the necrotic nodule shows an irregular or spiculated margin with suspicious microcalci cation, it is necessary to distinguish it from tumor recurrence with pathologic con rmation (14).…”

Does lipofilling after oncologic breast surgery increase the amount of suspicious imaging and required biopsies?—A systematic meta‐analysis

“…Yet, every surgery or traumatic procedure to the breast or to tissue in general can cause inflammatory and remodeling processes. Fat necrosis makes up to 2.75% of all lesions in the breast . The most common cause is trauma followed by breast surgery with adjuvant radiotherapy, the prevalence in these cases is estimated to be up to 25% .…”