Inflammatory Breast Disease


Mastitis describes inflammation of the breast tissue, both acute or chronic.

It most commonly affects pre-menopausal women, but there is also a small but significant prevalence in neonates when the breast bud is enlarged and prone to infection.

By far the most common cause is from infection, typically through S. Aureus however enterococci or anaerobic pathogens may also cause inflammation.


Mastitis can be classed by location or by lactation-status:

  • Lactational mastitis is very common and is seen in up to a third of breastfeeding women. It usually presents during the first 3 months of breastfeeding or during weaning.
    • It is associated with cracked nipples and milk stasis (often caused by poor feeding technique), and is more common with the first child.
  • Non-lactational mastitis most commonly occurs in younger women. The inflammation is usually located centrally*, in non-dilated periareolar ducts and should not be confused with duct ectasia (older age group and less marked inflammation)
    • Tobacco smoking is an important risk factor which is believed to damage the sub-areolar duct walls, predisposing to bacterial infection

*Occasionally, non-lactational mastitis can occur in the peripheral breast, often associated with underlying co-morbidity such as diabetes or steroid treatment. An important example is granulomatous lobular mastitis, a rare chronic infection resulting in abscess formation that is resistant to antimicrobial treatment.

Mastitis can also be associated with a skin infection such as cellulitis or a sebaceous cyst. It most commonly affects the lower breast and is associated with obesity, large breasts, eczema, and poor hygiene.

The infection is often chronic and should be prevented by promoting regular washing and drying of the breasts; antifungal or steroid creams can be used for any topical control required.

Clinical Features

Mastitis presents with tenderness, redness, and swelling over the area of infection. It can be associated with nipple retraction and discharge. These changes are generalised and it is important to ensure there is no localised infection (i.e. abscess development).


Mastitis is best managed with early broad spectrum antibiotics (such as co-amoxiclav and flucloxacillin) and simple analgesics.

In lactational mastitis, continued milk drainage or feeding is recommended. Cessation of breastfeeding using dopamine agonists (such as Cabergoline) can be considered in women with persistent or multiple areas of infection.


Breast abscesses are painful accumulations of pus lined with granulation tissue and can follow all types of acute mastitis. Abscesses present with local signs of inflammation (erythema, pain, and a fluctuant swelling) often associated a swinging fever. A suspected abscess can be confirmed via an ultrasound scan if there is any doubt regarding the diagnosis.

The initial cellulitic phase is fully reversible with prompt empirical antibiotics (e.g. flucloxacillin) and needle aspiration. More advanced abscesses may require incision and drainage* under a local anaesthetic.

*An important complication of drainage of a non-lactational abscess is the formation of a mammary duct fistula (a communication between the skin and a subareolar breast duct), which, whilst they can be managed surgically with a fistulectomy and antibiotics, can often recur.

Breast Cysts

Cysts are epithelial lined fluid filled cavities, which form when lobules become distended due to blockage, usually in the perimenopausal age group. Cysts make up 15% of presentations with palpable breast masses and 7% of women will experience one during their lifetime.

Clinical Features

They can present singularly or with multiple lumps and can affect one or both breasts. On palpation, cysts appear as distinct smooth masses and may be tender.


Fig. 1 – A fluid-filled cavity, as demonstrated by ultrasound scanning

Cysts can be identified by their typical halo shape on mammography and can usually be definitively diagnosed using ultrasound (fluid filled cavity), as seen in Fig. 1.

Symptomatic or undeterminable cystic masses may be aspirated, either freehand or using ultrasound. Cancer may be excluded if the fluid is free of blood or the lump disappears, otherwise the cystic fluid should be sent for cytology.


Once diagnosed, cysts usually require no further management and self-resolve, however women are at a higher risk of these recurring. Larger cysts can be aspirated for aesthetic reasons or patient reassurance.


Around 2% of patients with cysts have carcinomas on presentation, although most of these are incidental findings not related to the cyst itself. Patients with cysts also have a 2-3 times greater risk of developing breast cancer in the future.

Some women may develop fibroadenosis (fibrocystic change) caused by multiple small cysts and fibrotic areas. Although benign, it is often associated with tenderness and asymmetry, hence this fibrosis can often mask malignancy.

Most patients can be effectively managed with appropriate analgesia. Any cyclical pain may be treated with high dose gamolenic acid (GLA) or danazol.

Mammary Duct Ectasia

Duct ectasia is the dilation and shortening of the major lactiferous ducts. It is a common presentation in menopausal women, with 40% of women having significant duct dilatation by the age of 70.

Clinical Features

Fig. 2 – A mammogram demonstrating dilated calcified ducts, features in keeping with mammary duct ectasia

Duct ectasia often presents with coloured green/yellow nipple discharge, a palpable mass, and / or symmetrical slit-like nipple retraction.


Duct ectasia can be identified by mammography by dilated calcified ducts, without any other features of malignancy.

If biopsied, the mass classically contains multiple plasma cells on histology, which is often referred to as ‘plasma cell mastitis’.


It can be managed conservatively unless radiological findings cannot rule out malignancy. Unremitting nipple discharge can be treated with a total or subtotal duct excision.

Fat Necrosis

Fat necrosis is a common condition caused by an acute inflammatory response in the breast, leading to ischaemic necrosis of fat lobules.

Fig. 3 – Fat necrosis, as seen on histology

It is often referred to as traumatic fat necrosis due to its association with trauma, however blunt trauma to the breast is only implicated in 40% cases, with previous surgical and radiological intervention making up the remaining proportion.

Clinical Features

Fat necrosis is usually asymptomatic or presenting as an obvious lump, however less commonly can present with fluid discharge, skin dimpling, pain and nipple inversion.

The acute inflammatory response can persist, causing a chronic fibrotic change which can develop into a solid irregular lump.


Fat necrosis may be suggested by a positive traumatic history and/ or a hyperechoic mass on ultrasound.

More developed fibrotic lesions will mimic carcinoma on mammogram, appearing as calcified irregular speculated masses and the solid irregular lump may feel suspicious on palpation. Therefore a core biopsy is often taken to categorically rule out malignancy.


Fat necrosis is self-limiting and usually only requires analgesic management and reassurance.

Key Points

  • Mastitis is inflammation of the breast tissue, best treated with early broad spectrum antibiotics
  • Breast cysts are epithelial lined fluid filled cavities within the breast tissue, usually requiring no further management and self-resolve
  • Duct ectasia often presents with coloured green/yellow nipple discharge, yet is best managed conservatively
  • Fat necrosis is ischaemic necrosis of fat lobules, associated with trauma in 40% of cases


Question 1 / 4
What is the recommended first-line management for simple lactational mastitis?


Question 2 / 4
What proportion of women presenting with a palpable breast mass are cysts?


Question 3 / 4
What is mammary duct ectasia?


Question 4 / 4
How does fat necrosis appear on ultrasound?


Rate This Article


Average Rating: