- This may be blunt force trauma (e.g. seatbelt in car accident), breast surgery (including breast conserving surgery and mastectomy with or without breast reconstruction), or biopsy.
- Other causes include radiotherapy, anticoagulation treatment and breast infection.
- Smoking, obesity and increasing age alongside recent surgical procedures for breast cancer all increase the risk of developing fat necrosis of the breast.
- In fat necrosis of of the breast, intra-cellular components spill into the interstitial space, usually following trauma, and both types of cell death result.
- It is typically a sterile inflammatory process.
- Early macroscopic appearances include haemorrhagic foci, ‘foam cells’ (fat-filled macrophages), and necrotic lipid material.
- Liquefactive necrosis may occur in some cases, whereby extensive enzymatic digestion of the adipose tissue causes a cystic lesion with a liquid central cavity to form.
- Later, fibrosis and calcification occur at the peripheries of the lesion as it resolves.
However, frank clinical signs include:
- Palpable mass or masses in the breast
- These are typically ‘stony hard’ (66%), and may be adherent to the skin (50%)
- There may be associated ecchymosis or erythema
- A suggestive clinical history e.g. recent surgery or trauma may help the diagnosis
- Clinical features are typically all highly suggestive of breast malignancy and fat necrosis is therefore a diagnosis of exclusion.
- Malignancy must remain the primary differential, even if there is a clinical history of breast trauma.
- Blood tests
- If co-existing breast infection is suspected, full blood count, U&E, CRP and blood cultures are appropriate.
- Breast ultrasound to characterise lesion
- Mammography: may show lipid cysts, pathognomonic of fat necrosis, or areas of fibrosis or calcification indistinguishable from malignancy. Mammography may also be normal in 9% of cases.
- MR imaging may be considered.
- Core needle biopsy to rule out malignant pathology
In patients where malignancy has been excluded:
- If there are no troubling symptoms then follow-up with imaging and clinical examination is appropriate as the most likely course of this benign condition is normalisation of the fatty tissue without treatment.
- In symptomatic patients, or with increasing size of benign lesion at follow-up, surgical excision is possible. Some lesions may be amenable to the less invasive vacuum-assisted biopsy for excision
- Care must be taken at all stages to ensure that malignancy has not been missed.