Mastitis and breast abscess in children and adolescents

INTRODUCTION — The clinical features, evaluation, and management of mastitis and breast abscess in children older than two months and adolescents will be discussed in this topic review. Mastitis and breast abscess in infants, lactational mastitis, and breast infections in adult women are discussed separately.

●(See "Mastitis and breast abscess in infants younger than two months".)

●(See "Lactational mastitis".)

●(See "Nonlactational mastitis in adults".)

●(See "Primary breast abscess".)

MICROBIOLOGY — In children and adolescents, mastitis is most commonly caused by Staphylococcus aureus but also may be caused by Enterococcus, Streptococcus pyogenes (group A Streptococcus), anaerobic streptococci, Pseudomonas, Streptococcus agalactiae (group B Streptococcus), and Bacteroides species [1-3]. Other unusual organisms such as Actinomycosis may be involved in patients whose infections are associated with nipple piercing [4]. (See "Body piercing in adolescents and young adults", section on 'Localized infection'.)

PATHOGENESIS — Mastitis in children ≥2 years and adolescents results from the introduction of bacteria into the ductal system [3]. It is more likely at puberty or within a few months of menarche, when breast changes and growth are at a peak [2,5]. Factors that predispose to breast infection in children and nonlactating adolescents include superficial injury to the breast (eg, due to breast manipulation during sexual activity, shaving or plucking periareolar hair, picking acne lesions of the chest, nipple piercing, insect bites), obesity, mammary duct ectasia, hidradenitis suppurativa, local skin infection, and epidermoid cysts [2,3,6-8]. Peripheral mastitis may be associated with diabetes mellitus, rheumatoid arthritis, glucocorticoid therapy, granulomatous disease, and blunt trauma [3].

CLINICAL FEATURES AND DIAGNOSIS — Nonlactational mastitis is uncommon in children. After the first two months of life, it generally occurs in children ≥8 years of age [1].

The diagnosis of mastitis can be made clinically in children and adolescents with characteristic clinical features: swelling, erythema, warmth, tenderness, and induration of the central or peripheral breast [1,8]. Breast abscess is indicated by fluctuance (picture 1). Purulent nipple discharge also may be present.

Neither laboratory nor imaging studies are necessary to diagnose mastitis or breast abscess. We obtain the following studies as clinically indicated:

●Gram stain and cultures – We obtain Gram stain and culture of nipple discharge if present or abscess fluid in patients with breast abscess. Positive Gram stain and/or culture support the diagnosis and guide antimicrobial therapy. (See 'Drainage of breast abscess' below and 'Antimicrobial therapy' below.)

We do not routinely obtain blood cultures in children and adolescents with mastitis or breast abscess unless they fail to respond to treatment. Blood cultures are of low yield unless the cellulitis is severe [9]. (See "Cellulitis and skin abscess: Epidemiology, microbiology, clinical manifestations, and diagnosis".)

●Complete blood count with differential – We obtain complete blood count with differential in patients with fever, systemic symptoms, abscess or potential abscess, or recurrent mastitis. Leukocytosis supports the diagnosis and may be used to follow the clinical course; measurement of other inflammatory markers (eg, erythrocyte sedimentation rate and C-reactive protein) usually is not necessary.

●Ultrasound imaging – Although ultrasonography is not necessary for the diagnosis of breast abscess, we use it to guide therapeutic and diagnostic needle aspiration. Ultrasound findings of breast abscess include irregular shape with ill-defined margins, a complex hypoechoic center, and thick echogenic wall [10].

DIFFERENTIAL DIAGNOSIS — The major consideration in the differential diagnosis of mastitis or breast abscess in children and adolescents is breast trauma. Trauma to the breast (eg, direct blows to the breast, seatbelt injury) may result in hematomas or fat necrosis, which can resemble a solid mass [2,8,11]. The solid mass distinguishes fat necrosis from mastitis (in which there is no distinct mass) and breast abscess (in which the mass is fluctuant). Breast ultrasonography may help to differentiate mastitis and breast abscess from sequelae of trauma [10]. (See "Breast masses in children and adolescents", section on 'Breast trauma'.)

Conditions that infrequently mimic mastitis or breast abscess in older children and adolescents include [12]:

●Lymphangioma – Lymphangiomas (eg, cystic hygromas) are malformations of the lymphatic system that are characterized by thin walled cysts; they rarely occur in the breast [13,14]. The absences of erythema, tenderness, and warmth distinguish lymphangioma from mastitis and breast abscess.

●Mammary duct ectasia (ie, distension of subareolar ducts with fibrosis and inflammation) – Mammary duct ectasia may be associated with a bloody or dark green-brown nipple discharge in children and adolescent [15]. It also may predispose to infection. Ultrasonography demonstrates retroareolar, dilated, anechoic tubular structures, possibly with echogenic debris [10]. (See "Breast masses in children and adolescents", section on 'Mammary duct ectasia'.)

●Superficial thrombophlebitis of the thoracoepigastric vein (Mondor disease) – Clinical features that distinguish superficial thrombophlebitis of the thoracoepigastric vein from mastitis or breast abscess include a thickened tender cord that is painful, erythematous, and swollen.

●Carcinoma – Breast cancer is exceedingly rare in adolescents. The most common finding of breast cancer in adolescents is a hard, irregular mass, which may or may not be fixed to the underlying tissue. The hardness of the mass distinguishes carcinoma from mastitis, in which there is no distinct mass, and breast abscess, which is typically fluctuant. (See "Breast masses in children and adolescents", section on 'Breast cancer'.)

MANAGEMENT — Management of mastitis and breast abscess consists of supportive care, antimicrobial therapy, and drainage (if there is a drainable abscess).

Supportive care — Supportive care for children and adolescents with mastitis includes application of warm compresses and provision of breast support (as necessary) [3,7].

Antimicrobial therapy

Choice of regimen — No randomized controlled trials have evaluated antibiotic regimens for mastitis in older children and adolescents. Recommendations for treatment are based upon the most likely causative pathogens and response to therapy described in observational studies [1,6].

The choice of antibiotics is guided by the Gram stain if one is available and a pathogenic organism is identified (eg, antistaphylococcal therapy for gram-positive cocci in clusters). If a Gram stain is not available, we provide empiric coverage for S. aureus and group A Streptococcus (GAS) [2,7].

●Immune competent, well-appearing, and no systemic symptoms – For immune-competent children and adolescents with mastitis or breast abscess who are well appearing and without systemic symptoms, we use oral antimicrobial therapy (table 1).

Appropriate empiric oral regimens include monotherapy with one of the following [16]:

•Cephalexin 25 to 50 mg/kg per day orally in three or four doses (maximum daily dose: 2 g)

•Clindamycin 30 to 40 mg/kg per day orally in three or four doses (maximum daily dose: 1.8 g)

Clindamycin is suggested in areas with increased incidence of community-associated methicillin-resistant S. aureus (CA-MRSA; more than 10 percent of community isolates)

•Cloxacillin (not available in the United States) 25 to 50 mg/kg per day orally in four doses (maximum daily dose: 2 g)

•Dicloxacillin 25 to 50 mg/kg per day orally in four doses (maximum daily dose: 2 g)

Trimethoprim-sulfamethoxazole (TMP-SMX) 8 to 12 mg TMP/kg per day orally in two doses (maximum daily dose of TMP component: 320 mg) is another alternative in areas with an increased incidence of CA-MRSA. However, TMP-SMX is not active against GAS.

●Ill-appearance, systemic symptoms, rapid progression, or immune compromise – For children and adolescents with mastitis or breast abscess who are ill appearing, have systemic symptoms, have rapid progression of erythema, or are immunocompromised, we begin treatment parenterally. Patients may be transitioned from parenteral to oral therapy when fever and systemic symptoms have resolved and localized findings have improved.

•CA-MRSA not a concern – Appropriate empiric parenteral regimens if CA-MRSA is not a concern include monotherapy with one of the following [16]:

-Cefazolin 50 to 100 mg/kg per day intravenously (IV) in three doses (maximum daily dose: 3 g)

-Nafcillin 150 to 200 mg/kg per day IV in four to six doses (maximum daily dose: 12 g)

-Oxacillin 150 to 200 mg/kg per day IV in four to six doses (maximum daily dose: 12 g)

•CA-MRSA a concern or life-threatening penicillin allergy – Appropriate parenteral regimens if CA-MRSA is a concern or the patient has a life-threatening penicillin allergy include [16]:

-Clindamycin 30 to 40 mg/kg per day IV in three or four doses (maximum daily dose 2.7 g)

-Vancomycin (table 2)

(See "Penicillin allergy: Immediate reactions" and "Allergy evaluation for immediate penicillin allergy: Skin test-based diagnostic strategies and cross-reactivity with other beta-lactam antibiotics".)

Our recommendations for antimicrobial therapy are generally consistent with the 2014 Infectious Diseases Society of America guidelines on the diagnosis and management of skin and soft-tissue infections [16].

Duration of therapy — The total duration of systemic antimicrobial therapy for mastitis and breast abscess is not well studied. It depends upon the type of infection and clinical response. We generally treat for 7 to 10 days and extend or adjust the course if the infection has not improved within 10 days. However, a minimum duration of five days may be adequate provided the patient improves clinically and the course is uncomplicated [16]. (See 'Failure to respond' below.)

Drainage of breast abscess — In addition to antimicrobial therapy, breast abscess may require ultrasound-guided fine needle aspiration or incision and drainage if there is no response to antimicrobial therapy [8,17].

During drainage, care must be taken to avoid the breast bud in prepubertal/pubertal children [3,17]. If incision and drainage is necessary, it should be performed by appropriately trained personnel (eg, a breast surgeon, pediatric surgeon, or breast radiologist) to minimize the risk of hypoplasia or scarring.

RESPONSE TO THERAPY

Monitoring response — Response to therapy is indicated by clinical improvement within 24 to 48 hours of appropriate antibiotic therapy. As with all soft tissue infections, use of a marking pen to outline the erythematous area allows the clinician to assess the patient's response to therapy. Rapid progression of erythema supports use of parenteral antibiotics or need to reassess choice of antibiotics.

Failure to respond — Possible explanations for failure to respond to empiric or directed antimicrobial therapy within 24 to 48 hours include [8,17]:

●Resistance to initial antibiotic

●Inadequate concentration of antibiotic (eg, if administered orally)

●Inadequate abscess drainage (if drainage was performed), recurrent abscess, or development of a new abscess

●Incorrect diagnoses (see 'Differential diagnosis' above)

Ultrasonography may identify residual, recurrent, or new abscesses that require drainage, particularly if induration makes it difficult to assess fluctuance. Ultrasonography can also be used to guide the drainage procedure if drainage is necessary.

For patients in whom cultures were not obtained or in whom cultures remain negative, a resistant pathogen is another possible explanation for treatment failure. In such patients, it may be necessary to broaden empiric antimicrobial therapy to include activity against resistant pathogens not addressed in the initial regimen (eg, switching from cephalexin to clindamycin if methicillin-resistant S. aureus is a concern, adding coverage for less frequent pathogens) or to switch from oral to parenteral therapy.

PROGNOSIS — Most children and adolescents with mastitis or breast abscess recover without physical sequelae. Patients with S. aureus mastitis are at risk for subsequent S. aureus infections at other sites. (See "Methicillin-resistant Staphylococcus aureus infections in children: Epidemiology and clinical spectrum".)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Skin and soft tissue infections".)

SUMMARY AND RECOMMENDATIONS

●Microbiology – Staphylococcus aureus is the most frequent cause of breast infection in children and adolescents. Other causes include Enterococcus, group A Streptococcus (GAS), anaerobic streptococci, Pseudomonas, group B Streptococcus, and Bacteroides species. (See 'Microbiology' above.)

●Clinical features and diagnosis – A clinical diagnosis of mastitis and/or breast abscess can be made in patients with swelling, erythema, warmth, tenderness, induration, and/or fluctuance of the breast. Isolation of a pathogen on Gram stain or culture of purulent nipple drainage or abscess fluid (if present) support the diagnosis and direct antimicrobial therapy. (See 'Clinical features and diagnosis' above.)

●Antimicrobial therapy – Initial antimicrobial therapy is based upon the Gram stain if one is available and a pathogenic organism is identified. If Gram stain is not available, we provide empiric coverage for S. aureus and GAS. (See 'Antimicrobial therapy' above.)

•For immune-competent children and adolescents with mastitis or breast abscess who are well appearing and without systemic symptoms, we initiate antimicrobial therapy orally. Appropriate oral empiric agents include dicloxacillin, cloxacillin (not available in the United States), cephalexin, and clindamycin (table 1). Clindamycin may be necessary in areas with increased incidence of community-associated methicillin-resistant S. aureus (CA-MRSA). Trimethoprim-sulfamethoxazole is another alternative for areas with increased incidence of CA-MRSA, but it does not provide adequate coverage for GAS.

•For children and adolescents with mastitis or breast abscess who are ill appearing, have systemic symptoms, have rapid progression of erythema, or are immunocompromised, we initiate antimicrobial therapy parenterally. Appropriate parenteral empiric agents include cefazolin, nafcillin, or oxacillin if CA-MRSA is not a concern and clindamycin or vancomycin if CA-MRSA is a concern (table 1).

We generally treat mastitis or breast abscess in children and adolescents with antimicrobial therapy for 7 to 10 days and extend or adjust the course if the infection has not improved within 10 days. (See 'Duration of therapy' above.)

●Drainage of breast abscess – Breast abscess may require ultrasound-guided needle aspiration to direct antibiotic management or incision and drainage in addition to antimicrobial therapy if there is no response to antimicrobial therapy. Incision and drainage should be performed by appropriately trained personnel (eg, a breast surgeon, pediatric surgeon, or breast radiologist). (See 'Drainage of breast abscess' above.)

●Response to therapy – Response to therapy is indicated by clinical improvement within 24 to 48 hours of appropriate antibiotic therapy. Failure to respond to antimicrobial therapy may indicate a resistant pathogen, inadequate concentration of antibiotic, abscess (residual, recurrent, or new), or incorrect diagnosis. (See 'Response to therapy' above.)

●Prognosis – Most patients with mastitis or breast abscess recover without sequelae. Patients with S. aureus mastitis are at risk for subsequent S. aureus infections at other sites. (See 'Prognosis' above.)