Breast Abscess

Definition

Classification

1. Lactational (Puerperal) Abscess

• Occurs in breastfeeding women, most commonly in the first 6 weeks postpartum or during weaning
• Results from milk stasis combined with bacterial entry through cracked or abraded nipples
• Most common organism: Staphylococcus aureus (including MRSA) and streptococci from the nursing infant's mouth

2. Non-Lactational Abscess

• More common overall (86% of all cases)
• Associated with smoking, diabetes, and obesity
• Can also follow nipple piercing or breast implant complications
• Often caused by mixed flora (aerobic and anaerobic), especially in recurrent cases
• Organisms: S. aureus most common (51.3%); MRSA in up to 8.6-20% of cases; mixed anaerobes (13.7%); anaerobic cocci, Bacteroides, Corynebacterium, E. coli, P. mirabilis

3. Subareolar Abscess (Periductal Mastitis / Duct Ectasia)

• A relapsing form unique to non-lactating women
• Associated with squamous metaplasia of the lactiferous ducts, with obstruction by inspissated debris
• Strongly linked to smoking and diabetes
• Can lead to nipple retraction, subareolar masses, and lactiferous duct fistula (mammillary sinus) to periareolar skin
• Mixed aerobic and anaerobic flora typical

Risk Factors

• Lactation (especially first 6 weeks)
• Smoking (also increases recurrence risk)
• Diabetes
• Obesity
• African American race
• Nipple piercing or breast implants
• Poor hygiene during breastfeeding

Clinical Features

• Cellulitis phase: diffuse erythema, no discrete fluctuant mass; ultrasound shows thickened hyperechoic skin
• Abscess phase: localized fluctuant mass; ultrasound shows inhomogeneous, hyperechoic collection, often multiloculated

Important: Failure to improve with antibiotics requires urgent surgical consultation and possible biopsy to exclude inflammatory carcinoma. Inflammatory carcinoma can closely mimic a breast abscess. - Tintinalli's Emergency Medicine

Investigations

• Ultrasound (US): First-line imaging - confirms abscess vs. cellulitis, identifies loculations, guides aspiration. Appearance: inhomogeneous, hyperechoic mass with posterior acoustic enhancement
• Pus culture and sensitivity: Always send aspirated pus, including MRSA screening
• Milk culture: In lactating patients; if delivered in hospital, assume penicillin-resistant Staphylococcus
• Mammography: Recommended in women >30 years, performed after the acute phase resolves
• Biopsy: Required if erythema persists despite treatment to rule out inflammatory carcinoma

Management

Step 1 - Early/Cellulitis Stage (No Frank Abscess)

• Antibiotics alone may be curative
• Apply heat; encourage continued breast emptying (lactating)

Step 2 - Frank Abscess: Needle Aspiration (First-Line)

• Ultrasound-guided needle aspiration is now the standard of care for most breast abscesses
• For abscesses <3 cm: single-needle aspiration
• For abscesses ≥3 cm: ultrasound-guided catheter drainage preferred
• Advantages over I&D: less scarring, does not interfere with breastfeeding, no procedural sedation required
• Mean of 3.5 aspirations required for complete resolution; repeat daily or every other day
• A single aspiration is sufficient in ~50% of non-lactational cases

Step 3 - Surgical Incision and Drainage (I&D)

• Skin compromise (thinning, necrosis) overlying the abscess
• Failure to resolve after needle aspiration + antibiotics
• Multiloculated abscesses (usually require general anaesthesia)

1. Radial incision near nipple/areola (to minimize duct damage); follow Langer's lines elsewhere
2. Enter abscess cavity with scissors
3. Send swab of pus for culture
4. Digitally break down all loculi into one large cavity

1. Curettage or dissection of necrotic material, then dry gauze wipeout
2. If drainage is difficult: counter-incision in the dependent (lower) part + soft rubber drain
3. Dry dressings, wool padding, supporting bandage; continue antibiotics

Specific Situations

Lactating Women

• Do not stop breastfeeding from the affected breast in early mastitis; continue to empty the breast (reduces milk stasis)
• If abscess forms: percutaneous drainage + continue breastfeeding (non-infected side at minimum)
• Breastfeeding can usually be resumed from the affected side after drainage

Antibioma (Sterile Abscess)

• If antibiotics are continued without drainage, pus may be sterilized, forming a hard, palpable mass resembling carcinoma
• Diagnosed by aspirating pus that yields no bacterial growth
• Treated by aspiration or formal drainage

Subareolar / Recurrent Abscess

• Multiple aspirations often required
• Definitive treatment (after the acute infection resolves): excision of the entire subareolar duct complex
• I&D alone has a high recurrence rate
• Rarely, repeated infections require excision of the nipple and areola
• Lactiferous duct fistula (mammillary sinus) is confirmed as the cause of reinfection in virtually all recurrent cases
• Counsel patients on smoking cessation

Differential Diagnosis

• Cellulitis
• Mastitis
• Periductal mastitis / duct ectasia
• Ruptured breast cyst
• Inflammatory breast carcinoma (most important to exclude)
• Metastatic cancer
• Tuberculosis of the breast
• Paget's disease
• Idiopathic granulomatous mastitis

Key Points Summary

Breast Abscess

Classification

1. Lactational (Puerperal) Abscess

• Occurs during breastfeeding, most commonly in the first 6 weeks postpartum or during weaning
• Precipitated by milk stasis (missed feeds, weaning) + bacterial entry through cracked/abraded nipple
• Organism from the nursing infant's mouth: S. aureus (including MRSA), streptococci
• Mastitis incidence in lactating women: 2-33%

2. Non-Lactational Abscess

• The more common form (86%)
• Associated with smoking, diabetes, obesity
• Also linked to nipple piercing, breast implants
• More likely to be multiloculated and caused by mixed flora

3. Subareolar Abscess / Periductal Mastitis

• Relapsing chronic form in non-lactating women
• Caused by squamous metaplasia of the lactiferous ducts → obstruction by inspissated debris
• Strongly linked to smoking
• Leads to: nipple retraction/inversion, subareolar mass, and lactiferous duct fistula (mammillary sinus) to periareolar skin
• Mixed aerobic + anaerobic flora

Microbiology

Risk Factors

• Lactation (especially cracked nipples)
• Smoking (increases incidence AND recurrence)
• Diabetes mellitus
• Obesity
• African American race
• Nipple piercing / breast implants
• Poor breastfeeding hygiene

Clinical Features

• Early stage (cellulitis predominates): diffuse, no discrete mass - diagnosis may be difficult
• Late stage: fluctuant, loculated mass; patient may appear toxic

Red flag: If erythema does not improve with antibiotics, inflammatory breast carcinoma must be excluded by biopsy. It can mimic infection exactly. - Tintinalli's Emergency Medicine

Investigations

• Breast ultrasound - first-line imaging
  • Cellulitis: diffuse thickened, hyperechoic skin, increased echogenicity of subcutaneous tissue
  • Abscess: inhomogeneous, hyperechoic mass; identifies loculations, confirms pus, guides aspiration
• Pus culture and sensitivity - always send aspirated material (MRSA screen)
• Milk culture - in lactating patients
• Mammography - recommended for women >30 years, done after acute phase resolves (not during)
• Core biopsy - if diagnosis uncertain, or erythema fails to resolve, to exclude carcinoma

Management

Step 1: Early Cellulitis / Mastitis (No Frank Abscess)

• Antibiotics alone may be curative - reassess at 48 hours
• Lactating: support breast with firm bandage; breastfeeding may be continued or discontinued (resumed later)
• Apply warmth; encourage continued breast emptying

Step 2: Frank Abscess - Ultrasound-Guided Needle Aspiration (First-Line)

• Abscess <3 cm: needle aspiration (repeat daily or every other day as needed)
• Abscess ≥3 cm: ultrasound-guided catheter drainage preferred
• Mean of 3.5 aspirations required for complete resolution
• A single aspiration is sufficient in ~50% of non-lactational cases
• Always send aspirated pus for culture

Step 3: Surgical Incision and Drainage (I&D)

• Compromise/thinning of overlying skin
• Failure to resolve after aspiration + antibiotics
• Multiloculated abscess not amenable to aspiration

1. Incision: radial near nipple/areola (to protect ducts); follow Langer's lines elsewhere
2. Enter abscess cavity with scissors; swab pus for culture
3. Digitally break down all loculi into one large cavity

1. Curette or dissect necrotic material; wipe out with dry gauze
2. If drainage is difficult: counter-incision in dependent (lower) part of breast + soft rubber drain
3. Dry dressings, wool padding, supporting bandage; continue antibiotics; dress frequently

Special Situations

Antibioma (Sterile Abscess)

• Occurs when antibiotics are continued without drainage - pus becomes sterilized
• Presents as a hard, discrete, palpable breast mass - closely resembles carcinoma
• Diagnosis: aspirate yields pus with no growth on culture
• Treatment: aspiration or formal drainage

Subareolar / Recurrent Abscess

• Acute phase: aspiration + antibiotics covering aerobic and anaerobic organisms; warm soaks
• Definitive treatment (after full resolution of acute infection): excision of the entire subareolar duct complex + IV antibiotic cover
• I&D alone has a high recurrence rate - lactiferous duct fistula is the cause of reinfection in virtually all recurrent cases
• Rarely: repeated infections require excision of the nipple and areola
• Always counsel on smoking cessation (major modifiable risk)

Differential Diagnosis

Summary Table

BREAST ABSCESS - Short Notes

Definition

Types

Causative Organisms

• #1: S. aureus (51%) - including MRSA (up to 20%)
• Streptococcus, mixed anaerobes, Bacteroides
• Subareolar: mixed aerobic + anaerobic flora

Risk Factors

• Lactation + cracked nipple
• Smoking (also causes recurrence)
• Diabetes, obesity
• Nipple piercing, breast implants

Clinical Features

• Pain, swelling, erythema, warmth
• Tender fluctuant mass
• Fever, chills, malaise
• Systemic toxicity in severe cases

Investigations

• Ultrasound - confirms abscess, guides aspiration
  • Inhomogeneous hyperechoic mass
• Pus culture + sensitivity (always)
• Mammography (women >30 yrs, after acute phase)
• Biopsy - if no improvement → exclude inflammatory carcinoma

Treatment

Antibiotics

Drainage

Surgical I&D Technique

1. Radial incision near nipple (protect ducts) / Langer's lines elsewhere
2. Enter with scissors → swab pus
3. Digitally break down loculi into one cavity
4. Curette necrotic tissue
5. Counter-incision + rubber drain if drainage poor
6. Dressings + antibiotics

Special Points

Differentials to Remember

• Inflammatory breast carcinoma ← most important (biopsy if no response to antibiotics)
• Mastitis, cellulitis, ruptured cyst
• Granulomatous mastitis, TB breast, hidradenitis suppurativa

High-Yield Points

1. 86% non-lactating, 14% lactating
2. US-guided aspiration = standard of care (not I&D first)
3. Smoking → recurrence → excise subareolar ducts
4. No response to antibiotics → biopsy to exclude carcinoma
5. Antibioma = sterile abscess = mimics cancer