Lactational mastitis is often preceded by either engorgement or a focally blocked duct. Patients may give a history of these associated symptoms before the development of the classic features of mastitis. Lactational mastitis is characterized by a focal, firm, erythematous, swollen, and painful area of one breast, plus a fever (higher than or equal to 100.4 degrees Fahrenheit). Patients often experience systemic symptoms such as chills, myalgias, and malaise.

Features of periductal mastitis include a periareolar or subareolar mass, that may be associated with pain and erythema. Patients may present with nipple inversion, thick nipple discharge, breast abscess, or draining fistulas.[22]

IGM most often presents with a firm, unilateral breast mass. Other findings can include nipple retraction, skin thickening, axillary adenopathy, ulceration, and abscess formation.[23] Many of these features overlap with the presenting features of breast malignancy, and this can sometimes be misdiagnosed early on. Patients with IGM can also experience extramammary manifestations, including arthralgias, episcleritis, and skin changes.[24]

The diagnosis of lactational mastitis is based on history and clinical findings. If there is concern that the patient may have a breast abscess, a breast ultrasound can be obtained. If an abscess is present, hypoechoic areas of purulent material will be seen. For patients with a severe infection that is unresponsive to initial antibiotic therapy, a culture of breast milk can be useful to guide appropriate antibiotic selection. However, this is not routinely needed. Similarly, if there is a concern for bacteremia in a patient with severe mastitis, blood cultures should be obtained. However, these are not a part of the routine workup.[11] 

Periductal mastitis is primarily a clinical diagnosis. If nipple drainage is present, gram stain and culture should be sent to identify any associated organisms. If there is an associated mass and concern for malignancy, ultrasound or mammography should be obtained.[11]

Because the clinical features of IGM overlap with those of breast cancer, a biopsy must be done to make this diagnosis. Core needle biopsy or excisional biopsy are both viable options. Because of the proposed association between hyperprolactinemia and IGM, a prolactin level may be sent. Ultrasound and mammography are not adequate to distinguish IGM from breast malignancy.[13]

The initial management of lactational mastitis is symptomatic treatment.[25] Continuing to fully empty the breasts has shown to decrease the duration of symptoms in patients treated both with and without antibiotics. Patients should be encouraged to continue to breastfeed, pump, or hand express.[19][8][9] If the patient stops draining the milk, further stasis occurs, and the infection will progress. Non-steroidal anti-inflammatory drugs (NSAIDs) can be used for pain control. Heat applied to the breast just before emptying can help increase milk letdown and facilitate with emptying.[25]Cold packs applied to the breast after emptying can help reduce edema and pain.

If the symptoms of lactational mastitis persist beyond 12 to 24 hours, antibiotics should be administered.[8][9] Because S. aureus is the most common cause, antibiotic therapy should be tailored accordingly. In the setting of mild infection without MRSA risk factors, outpatient treatment can be initiated with dicloxacillin or cephalexin. If the patient has a penicillin allergy, erythromycin can be used. If the patient has risk factors for MRSA infection, treatment options include trimethoprim-sulfamethoxazole (TMP-SMX) or clindamycin. TMP-SMX should be avoided in women who are breastfeeding infants less than 1-month-old, and in infants who are jaundiced or premature. If a patient requires hospitalization, empiric treatment with vancomycin should be initiated until cultures and sensitivities return. There are not sufficient studies on the appropriate duration of outpatient treatment, but most sources recommend a 10-14 day course.[10]

Periductal mastitis is treated empirically with amoxicillin-clavulanate. Alternative options include dicloxacillin plus metronidazole or cephalexin plus metronidazole. If an abscess is present, ultrasound-guided needle aspiration plus antibiotic therapy is the preferred management strategy.[11] Periductal mastitis is often a recurring condition. If a patient has recurrent infections, surgical excision of the inflamed ducts may be required.[26] 

The treatment of IGM remains controversial. Current treatment strategies vary broadly and can include observation, corticosteroids, immunosuppressants, antibiotics, and surgery.[23] IGM is a benign condition that typically resolves without treatment in an average of 5 months.[23] A recent study showed the time to resolution of symptoms did not differ in patients who were managed with medications and with those managed with observation and supportive care.[23] Surgical excision is an option, but there is a reported 10% recurrence, even with surgical treatment. If IGM is complicated by secondary infection, antibiotics should be chosen based on culture and sensitivities.

The differential diagnosis of the three forms of mastitis differs significantly. The common differential diagnoses for each are as follows:

Lactational mastitis

• Breast engorgement
• Clogged duct
• Breast abscess
• Galactocele
• Inflammatory breast carcinoma

Periductal mastitis

• Duct ectasia
• Breast abscess
• Breast carcinoma

Idiopathic granulomatous mastitis

• Breast carcinoma
• Wegeners granulomatosis
• Tuberculosis
• Sarcoidosis
• Breast abscess

The majority of patients with mastitis will recover with appropriate treatment. The recurrence rate for each type of mastitis varies as follows: 

• Lactational mastitis: 8%-30% [27][28]
• Periductal mastitis: 4%-28% [17]
• Idiopathic granulomatous mastitis: 20%-78% [29][30]

One study reported that 38% of patients with IGM reported significant scarring, and 29% reported long term pain.[30]

One of the most common complications of lactational mastitis is early termination of breastfeeding. The disease of the breast and associated pain are some of the most commonly cited reasons for early cessation of breastfeeding.[25][31] A breast abscess is another complication of lactational mastitis and occurs in 3% to 11% of patients.[32][25] The development of a breast abscess is more common if mastitis is not treated early.

Periductal mastitis and IGM can both be complicated by abscess or fistula formation. Both forms of non-lactational mastitis are associated with recurrence and can lead to scarring and deformity of the breast tissue.

Lactational mastitis usually develops after a period of incomplete drainage and milk stasis. It is important to educate patients on ways to limit this stasis to prevent mastitis. Things to discuss may include the appropriate frequency of feeding and proper infant latching technique. Nipple pain is a common complaint in breastfeeding women and may lead to less frequent nursing. This increases milk stasis, thus increasing their risk of developing mastitis. It is important to counsel patients on ways to manage and decrease their pain. Patients with lactational mastitis may feel inclined to stop breastfeeding during their period of illness, possibly due to a combination of the discomfort and pain, as well as the concern of passing the infection to their infant. Providers should ensure the patient that breastfeeding with mastitis is safe and that they should continue to do so if desired.[33] If the patient does not wish to continue to breastfeed, they should be counseled on the importance of continuing to empty the breasts and taught alternative methods such as the use of a breast pump or manual expression. 

In addition to patient education, provider education is equally important. One small study showed that some providers are misinforming patients with mastitis that they must stop breastfeeding while infected.[28] Not only does this increase the likelihood of the patient developing an abscess, but it also contributes to early termination of breastfeeding, which robs both the patient and the infant of the associated benefits.[33]

Periductal mastitis is found almost exclusively in smokers. Encouraging smoking cessation is important and may help reduce the risk of recurrent inflammation.

Take-home points

• One of the most important considerations in the treatment of lactational mastitis is the need to continue to empty the breasts – encourage patients to continue to breastfeed if desired, and if not, encourage the use of a breast pump or hand expression.
• Lactational mastitis can be managed conservatively with supportive measures for the first 12 to 24 hours. If symptoms do not improve after this period, antibiotics should be started.
• If symptoms of lactational mastitis do not improve in 24 to 28 hours, consider the possibility of a breast abscess, and obtain an ultrasound.
• Idiopathic granulomatous mastitis is a rare condition that is often mistaken for breast carcinoma. A biopsy must be done to diagnose this condition and to rule out more serious pathology.
• The majority of patients with mastitis can be managed as outpatients. Examples of scenarios in which a patient may require hospitalization include the following: hemodynamic instability, intolerance to oral intake, severe dehydration, and recurrent infection that has failed outpatient management.

Lactational mastitis is a common condition among breastfeeding women. There are several modifiable risk factors discussed in this article, such as feeding too infrequently, the use of certain nipple creams, poor latching techniques, and tight-fitting bras, that predispose women to this disease. Education soon after delivery to raise maternal awareness on these risk factors could potentially lead to decreased incidence of mastitis. An interprofessional team approach should be taken when educating these women. Input from the physician, nursing staff, and lactation consultant should be incorporated in a consolidated effort to help decrease the incidence of this disease.

While patients with lactational mastitis may seek care from their obstetrician, it is not uncommon for these patients to present to urgent care facilities, emergency departments, or family practice physicians for evaluation. For this reason, it is important for physicians in each of these settings to be aware of the appropriate management of this condition. All medical staff caring for patients with mastitis should be aware of the recommendation that these patients continue to breastfeed, and that sudden cessation of breastfeeding increases the risk of abscess formation.[Level 3][33]  

For patients seeking care in the emergency department, there are often long wait times, and during this time, pumping or nursing may be necessary. Some hospitals have pumps that are able to be checked out to patients while in the emergency department. Emergency physicians should be aware of their hospital policy to obtain a pump if one is needed. This can often be coordinated with either the lactation consulting team or the obstetrics team.

If a physician is unsure whether or not an antibiotic they are prescribing is safe to take while breastfeeding, they may recruit the expertise of a pharmacist to ensure that the patient is getting a medication that will allow her to continue to breastfeed her child.