Inflammation of the mammary gland: causes and treatment

Inflammation of the mammary gland is a spectrum of conditions encompassing lactational mastitis, non-lactational mastitis, and breast abscesses. Mastitis most often occurs in lactating women in the first weeks after childbirth due to nipple congestion and microcracks, but it also occurs outside of lactation, including periductal and periareolar forms. The physician's key task is to quickly distinguish uncomplicated inflammation from abscesses and rare oncological mimics, in order to initiate treatment promptly and avoid unnecessary breastfeeding restrictions. [1]

Current recommendations emphasize that in uncomplicated lactational mastitis, continued breastfeeding is safe and beneficial, and "sterilization" of household items outside of standard hygiene is not required. Premature discontinuation of breastfeeding worsens congestion and can lead to abscess formation. Supportive care focuses on correcting attachment, adequate breast drainage, and pain management. [2]

Non-lactational mastitis is less common, more common in smokers, and can be persistent, leading to fistula formation. Antibacterial therapy is prescribed initially more often than for mild lactational mastitis, and if the infiltrate persists, imaging is necessary to rule out an abscess. In complex cases, a multidisciplinary approach involving a surgeon and radiologist is helpful. [3]

A breast abscess is a localized collection of pus, often a complication of mastitis. Its symptoms overlap with those of tumors and hematomas, so ultrasound is the gold standard for verification. Treatment relies on ultrasound-guided puncture and drainage techniques plus antibiotics, with excellent results in most patients. [4]

Code according to ICD-10 and ICD-11

In the International Classification of Diseases, Tenth Revision, inflammatory diseases of the mammary gland are grouped under block N61. For clarification, subheading N61.0 "Mastitis without abscess" is often used, and if a purulent lesion is present, it is coded as "mammary gland abscess." Having separate codes simplifies routing, statistics, and the rationale for antibacterial therapy. [5]

In the International Classification of Diseases, Eleventh Revision, inflammatory conditions of the mammary gland are classified under section GB21, "Inflammatory Diseases of the Mammary Gland," with subtypes including "mammary abscess." Cross-referencing is provided for lactational mastitis and neonatal mastitis, facilitating more accurate contextualization. [6]

Table 1. Codes for inflammatory diseases of the mammary gland

Classifier	Chapter	Code	Name
ICD-10	Breast diseases	N61	Inflammatory diseases of the mammary gland
ICD-10	Subheading	N61.0	Mastitis without abscess
ICD-11	Breast diseases	GB21	Inflammatory diseases of the mammary gland
ICD-11	Subtype	GB21.0	Breast abscess
ICD-11	Notes	-	Associations with postpartum and neonatal mastitis are indicated.

Epidemiology

Lactation mastitis is the most common form. Rapid surveys in recent years estimate its incidence at approximately 10 percent among breastfeeding mothers, especially in the first six weeks after birth. The variability is due to calculation methods and differences in breastfeeding counseling, but the trend is consistent: the early postpartum period is the highest risk period. [7]

Abscesses develop as a complication in a small percentage of patients with mastitis, but require special consideration as they lead to drainage procedures. In large practices, abscesses constitute a significant proportion of hospitalizations for breast disease, although successful puncture treatment allows for the avoidance of incisions in most cases. [8]

Non-lactational mastitis is less common, but more likely to recur and is associated with smoking and periductal changes. These cases are frequently reported in outpatient clinics and require careful antibacterial therapy, as pathogens and resistance patterns may differ from those seen in lactation situations. [9]

Hospital reviews in recent years have noted the sustainability of these approaches: initial examination, breastfeeding support, early ultrasound when in doubt, and a clear threshold for abscess drainage. This reduces the duration of symptoms and the incidence of surgical incisions. [10]

Reasons

Lactation mastitis is caused by a combination of congestion and bacterial colonization through a damaged nipple. Coagulase-negative staphylococci and Staphylococcus aureus are most commonly isolated, while mixed flora is less common. Critically important factors that contribute to congestion include improper attachment, infrequent feedings, and pressure from tight underwear. [11]

Non-lactational mastitis is typically associated with periductal inflammation, smoking, skin microtrauma, nipple piercing, and disruptions to the local microbiota. Pathogenesis includes the formation of viscous secretions, duct obstruction, and secondary infection. This explains the persistent course and tendency to fistulas in periareolar locations. [12]

An abscess develops when the inflammatory focus is inadequately drained and bacteria replicate in a confined space. In the early stages, the clinical presentation may be indistinguishable from a cellular infiltrate, so ultrasound can promptly identify the fluid component and proceed to a puncture. [13]

It's especially important to remember that inflammatory breast cancer is a "mask" for mastitis. A rapid onset with skin swelling, "orange peel" appearance, nipple retraction, and a poor response to antibiotics are cause for concern. If suspected, the patient should be immediately referred for oncological care. [14]

Risk factors

The first weeks postpartum, cracked nipples, difficult attachment, missed feedings, and constricting breastfeeding accessories are significant factors for lactation mastitis. Eliminating these factors reduces the need for antibiotics and prevents abscess formation. [15]

Smoking is a significant predictor of non-lactational mastitis and periareolar abscesses. Additional risks include nipple piercing, diabetes, immunocompromised conditions, and obesity. This group is more likely to require early antibiotic treatment and a lower threshold for imaging. [16]

Recurrent mastitis episodes are more likely to occur with unresolved breastfeeding issues, premature weaning, and chronic nipple trauma. Counseling and adjustments to breastfeeding technique reduce recurrence and duration of symptoms. [17]

Hospital observations show that late presentation and self-treatment increase the risk of abscess formation. Early use of ultrasound when an infiltrate persists facilitates faster puncture and shortens the duration of the illness. [18]

Table 2. Risk factors for mastitis and abscess

Context	Risk factors	Clinical significance
Lactation	Cracked nipples, infrequent feedings, engorgement, tight underwear	They increase pain and increase the risk of bacterial infection.
Non-lactational	Smoking, piercing, periductal changes	Tendency to periareolar abscesses and fistulas
Both groups	Diabetes mellitus, immunodeficiency, obesity	More severe course, slower response to therapy
Repeated episodes	Unresolved attachment and drainage issues	Risk of recurrence and abscess

Pathogenesis

Microcracks in the nipple and milk stagnation create conditions for bacterial penetration and growth. This triggers inflammation, which clinically manifests as pain, swelling, and hyperemia. If drainage is not restored, a purulent cavity forms. The transition from infiltrate to abscess is a continuum, where the critical moment is detected by ultrasound. [19]

The mammary gland is rich in ducts and fatty tissue, predisposing it to localized infection dissemination across anatomical planes. In the periareolar region, the proximity of ducts to the skin explains the predisposition to fistula formation in non-lactational mastitis. This requires earlier intervention and careful selection of antibiotics. [20]

The bacterial spectrum varies depending on the context. During lactation, staphylococci predominate, while in non-lactational forms, mixed aerobic-anaerobic flora is more common. This influences the empirical choice of antibiotics and the duration of treatment. [21]

Finally, there are non-infectious conditions that mimic mastitis: inflammatory carcinoma, granulomatous mastitis, and injection reactions. These require different management, so a poor response to adequate treatment is a signal to reconsider the diagnosis and perform a biopsy. [22]

Symptoms

Classic signs include pain, swelling, localized redness, and a feeling of warmth, sometimes accompanied by fever and a deterioration in well-being. Breastfeeding mothers often experience pain when latching on, a feeling of incomplete breast emptying, and nipple soreness. These symptoms develop rapidly, over a period of hours or a couple of days. [23]

With an abscess, there are additional signs of fluctuation, increasing local pain, sometimes temperature fluctuations, and a persistent infiltrate despite antibiotic treatment. The external image is not always reliable, so if in doubt, ultrasound is indicated. [24]

Non-lactational mastitis often presents with periareolar tenderness and swelling and may be accompanied by nipple discharge and redness, with a tendency to recur. Patients often report smoking and local procedures in the nipple area. [25]

Red flags requiring oncological alertness include: rapidly spreading redness with swelling of the skin and an "orange peel" appearance, nipple retraction, and a poor response to antibiotics within a few days. In these cases, urgent follow-up examination according to the oncological protocol is necessary. [26]

Classification, forms and stages

It is useful to distinguish three groups: lactational mastitis without abscess, non-lactational mastitis without abscess, and mammary gland abscesses. Each group has its own triggers, microbiology, and first-line management, ranging from breastfeeding support to early drainage. [27]

Lactation mastitis is divided into early uncomplicated and complicated (suspected abscess, severe systemic reaction, immunodeficiency). This determines the threshold for prescribing antibiotics and the indications for imaging. [28]

Non-lactational mastitis is often periareolar in nature and is classified by the presence of fistulas and recurrences. For fistulas and recurrent episodes, a plan is developed in consultation with the surgeon, including duct sanitation and smoking cessation, which reduces the recurrence rate. [29]

Abscesses are classified as superficial, periareolar, and deep. For all types, the standard approach is ultrasound guidance with puncture drainage, repeated as needed, reducing the need for incisions. [30]

Table 3. Practical classification of inflammatory conditions of the breast

Group	Context	First steps	Frequent solutions
Lactation mastitis	Breastfeeding period	Feeding support, pain relief	Antibiotics as indicated, ultrasound if in doubt
Non-lactational mastitis	Outside of lactation, more often periareolar	Early antibiotics	Ultrasound, surgeon for relapses and fistulas
Abscess	Any context	Ultrasound for verification	Ultrasound-guided puncture drainage plus antibiotics

Complications and consequences

The main complication of mastitis is abscess formation, which requires invasive drainage. Delayed diagnosis increases the duration of disability and the risk of lactation interruption. Early ultrasound examination and a low threshold for puncture reduce these risks. [31]

In non-lactational forms, fistulas and chronicity are possible, especially in smokers. In this case, treatment of the lesions, correction of risk factors, and involvement of a surgeon in planning are important. Without addressing the underlying causes, relapses remain frequent. [32]

Cosmetic consequences include scarring from incisions and fistula tracts. The use of minimally invasive ultrasound drainage and puncture techniques reduces trauma and accelerates recovery, especially in young patients. [33]

Rarely, inflammatory breast cancer is hidden under the guise of inflammation. Lack of response to antibiotics and typical skin signs are grounds for urgent referral for oncological evaluation with biopsy. [34]

When to see a doctor

Immediate contact with a specialist is necessary if fever, increasing pain, rapidly spreading redness, or signs of fluctuation appear. It is especially important for breastfeeding women to continue breastfeeding until the examination, as emptying the breast is part of the treatment. [35]

If symptoms do not improve within two days with adequate support and pain relief, an assessment for the need for antibiotics and ultrasound is necessary. Delayed treatment increases the risk of abscess formation. [36]

Outside of lactation, a doctor should be consulted for any painful periareolar infiltrate, nipple discharge, or fistulas, especially in smokers. Antibacterial therapy should be started earlier than in cases of mild lactation. [37]

Red flags of oncological alertness include "orange peel" appearance, nipple retraction, poor response to antibiotics, and enlarged axillary lymph nodes. These signs require urgent further investigation through the oncological route. [38]

Diagnostics

The first step is a clinical assessment: temperature, pain severity, area of hyperemia, lactation status, condition of the nipples and regional lymph nodes. At the same time, the doctor discusses latching technique and feeding frequency, as this influences the management even when prescribing antibiotics. [39]

The second step is deciding on imaging. Ultrasound is indicated in cases of suspected abscess, persistent infiltrate after antibiotic therapy, severe pain with fluctuation, and in all questionable non-lactational cases. This is a quick and accurate way to visualize the fluid cavity and select the puncture site. [40]

The third step is microbiology as indicated. Routine milk culture is not necessary for typical uncomplicated lactational mastitis, but is useful in cases of relapse, severe mastitis, suspected resistant strains, or in immunocompromised patients. Pus from an abscess is always sent for culture, which helps narrow the treatment. [41]

The fourth step is biopsy and advanced imaging in atypical cases. A poor response to treatment, a "hard" infiltrate, and atypical skin changes are all indications for a targeted biopsy to rule out inflammatory cancer and specific granulomatous processes. [42]

Table 4. Diagnostic methods and their role

Method	What does it give?	Who is it indicated for?	Comments
Clinical examination	Degree of inflammation, lactation status	To everyone	Risk stratification basis
Ultrasound	Cavity detection, puncture navigation	If you suspect an abscess, if you have any doubts	Selection method
Milk seeding	Identification of the pathogen	Relapses, severe course	Not necessary in a typical mild case
Pus culture	Selection of antibiotics	For any abscess	Required
Biopsy	Exclusion of the oncological process	Poor response, atypical picture	Urgently according to indications

Differential diagnosis

A breast abscess can mimic a tumor or hematoma caused by trauma. This is difficult to distinguish without ultrasound, especially in dense tissue. Therefore, if an infiltrate persists or there is any doubt, an ultrasound evaluation is mandatory, followed by a diagnostic puncture if necessary. [43]

Inflammatory breast cancer can mimic mastitis, but is characterized by rapid progression, skin swelling, an "orange peel" appearance, and a poor response to antibiotics. These symptoms require a biopsy and prompt oncological evaluation. [44]

Granulomatous mastitis, skin infections, and autoimmune dermatoses can cause localized infiltrates and ulcers. A combination of clinical examination, ultrasound, and biopsy is helpful. A correct diagnosis can save weeks of ineffective therapy. [45]

In nursing mothers, nodular formations are often identified as lactoceles and galactoceles. These are fluid-filled cavities containing milk, which are clearly visible on ultrasound and are treated with a puncture if symptoms occur. If there is any doubt, the sample is sent for analysis. [46]

Table 5. Mastitis “masks” and differential diagnostic guidelines

State	What is similar?	What makes it different	The next step
Abscess	Pain, swelling, redness	Cavity on ultrasound, fluctuation	Puncture and drainage
Inflammatory cancer	Redness, swelling	Orange peel, poor response to antibiotics	Biopsy and oncologic route
Galactocele	Knot in a nursing mother	Liquid cavity with milk	Puncture in case of symptoms
Hematoma	Painful node after injury	Trauma-related, blood echostructure	Observation or evacuation as indicated

Treatment

The basic treatment for lactational mastitis is continued breastfeeding, corrected latch-on, and adequate breast drainage. This reduces congestion and accelerates recovery. Painkillers and anti-inflammatory medications, local cold applications, rest, and hydration are recommended. Hand hygiene and routine cleaning of the breast pump are sufficient; routine sterilization beyond the standard is not necessary. [47]

Antibiotics for lactational mastitis are prescribed in cases of severe systemic reactions, ineffective support for 48 hours, clear signs of bacterial infection, or in patients with risk factors. The initial regimen is based on staphylococci and local resistance. In cases of relapse or severe cases, microbiological testing and adjustment of therapy are recommended. [48]

In non-lactational mastitis, antibacterial therapy is initiated earlier, as spontaneous improvement with supportive measures is not expected. Oral regimens are typically selected taking into account the likely mixed flora and resistance risk factors, with revision based on culture results. If the condition worsens, rapid transition to imaging is indicated. [49]

An abscess requires drainage. In most cases, a puncture with a thick needle under ultrasound guidance, followed by lavage of the cavity and repeating the procedure if necessary, is sufficient. This is less traumatic than an incision, provides an excellent cosmetic effect, and has a high cure rate, especially with early treatment. Antibiotics are added if systemic symptoms or significant surrounding cellulitis are present. [50]

The choice of analgesia and anti-inflammatory medications is individual, but compatibility with lactation is considered during breastfeeding. Local cold and a supportive bra reduce pain. Warm compresses are applied carefully to avoid increasing swelling. Discussing household measures with a lactation consultant improves adherence. [51]

In cases of recurrent periareolar abscesses, smoking cessation and debridement of chronic lesions, including fistula tracts, are important. Sometimes, elective surgery is required to address periductal pathology to break the vicious cycle of recurrence. [52]

If clinical symptoms do not improve with adequate therapy, the physician reevaluates the diagnosis: extensive imaging, cultures, and sometimes a biopsy are performed to rule out inflammatory cancer and granulomatous processes. Tactics are changed based on new data, not just over time. [53]

The patient is explained the expected progress in advance: with proper management, pain and temperature typically subside within two days, and the infiltrate within a few days. A lack of such progress is a signal to adjust the plan. Clear expectations reduce anxiety and improve outcomes. [54]

Lactation support includes teaching effective pumping techniques when pain is present, assessing the baby's position, briefly initiating feeding from the healthy breast when severe pain is present, and then switching to the affected side for emptying. These techniques reduce congestion and speed up the resolution of inflammation. [55]

In complex cases, a short multidisciplinary consultation involving an obstetrician/gynecologist, breast surgeon, radiologist, and, if necessary, a dermatologist or oncologist is helpful. A team approach reduces the time to drainage, prevents unnecessary courses of antibiotics, and reduces the risk of cosmetic defects. [56]

Table 6. Antibacterial therapy: selection guidelines

Situation	Suspected pathogens	Approach to therapy
Lactation mastitis, mild course	Staphylococci	Support plus antibacterial therapy as indicated, review after forty-eight hours
Lactation mastitis, relapses or severe course	Staphylococci, possible resistance	Milk seeding, escalation based on results
Non-lactational mastitis	Mixed flora	Early oral antibiotics, assessment at forty-eight hours
Abscess	Polymicrobial flora	Puncture drainage, antibiotics for cellulitis or systemic reaction

Based on clinical summaries and primary care guidelines.[57]

Prevention

Prevention of lactational mastitis involves teaching proper latching technique, frequent and complete breast drainage, avoiding long intervals between breastfeeding sessions, protecting the nipples from injury, and choosing appropriate underwear. Early intervention by a lactation consultant significantly reduces the risk of recurrence. [58]

Hygiene measures should be reasonable: hand washing and routine cleaning of the breast pump are sufficient. Excessive sterilization has not been proven beneficial and creates unnecessary burden. Smoking cessation reduces the risk of non-lactation mastitis and recurrence of periareolar abscesses. [59]

After mastitis, a self-monitoring plan is helpful: pay close attention to early signs of congestion, promptly latch on, and seek medical attention at the first sign of symptoms. This reduces the likelihood of abscesses and interrupted lactation. [60]

In risk groups - diabetes mellitus, immunodeficiency - a lower threshold for medical contact at the first signs of inflammation and early imaging when in doubt is recommended to avoid missing an abscess. [61]

Forecast

With timely support and appropriate management, most episodes of lactational mastitis resolve without sequelae, and breastfeeding can be maintained. Puncture drainage of abscesses ensures rapid recovery with good cosmetic results in most patients. [62]

Non-lactational mastitis has a high tendency to recur, especially with continued smoking and periductal changes. A combination of measures—antibiotics, risk factor correction, and, if necessary, surgical debridement—reduces the recurrence rate. [63]

A lack of response to therapy is a reason to reconsider the diagnosis and rule out oncological and specific inflammatory processes. This approach reduces the likelihood of delaying a true diagnosis and improves the outcome. [64]

Overall, the long-term prognosis is favorable with early treatment, appropriate support, and the use of ultrasound to guide invasive procedures. This shortens the duration of symptoms and reduces the incidence of surgical incisions. [65]

Frequently Asked Questions

Can I continue breastfeeding if I have mastitis?
Yes. Lactation mastitis does not require stopping breastfeeding. In fact, adequate bowel movements are part of treatment. Technique should be adjusted and pain relief should be used if necessary. [66]

Do all breastfeeding mothers with mastitis need antibiotics?
No. In mild cases and the absence of systemic symptoms, supportive care and dynamic observation are sufficient. Antibiotics are added if there is no improvement within two days, if there is a high fever, a severe local infection, or if risk factors are present. [67]

How to recognize an abscess?
Suspicion arises with fluctuation, increased local pain, and persistence of the infiltrate despite therapy. Ultrasound confirms the diagnosis. Treatment involves ultrasound-guided puncture drainage and antibacterial support as indicated. [68]

When should you consider cancer?
If skin redness and swelling progress rapidly, an "orange peel" appearance develops, nipple retraction occurs, and there is no response to antibiotics, an urgent biopsy and oncological evaluation are necessary. [69]

Table 7. Step-by-step algorithm for conducting

Step	Action	Transition criterion
1	Clinical assessment, breastfeeding support, pain management	No improvement after two days or severe symptoms
2	Antibiotic decision-making based on context	Persistence of infiltrate, fluctuation, severe pain
3	Ultrasound if there is any doubt about an abscess or non-lactational process	Cavity detected - drainage
4	Puncture drainage with content culture	Repeated puncture in case of residual cavity
5	Reconsideration of diagnosis in case of poor response	Biopsy and oncological route according to indications