Breast abscess/mastitis (SURG)

Question 1

Define mastitis.

Answer 1

Inflammation of the breast with or without infection

Question 2

What are the two types of mastitis with infection?

Answer 2

• lactational (puerperal) - milk stasis/overproduction + bacteria entry through traumatised nipple
• non-lactational (e.g. duct ectasia - milk duct widens and walls thicken = obstructive mastopathy, prone to infection)

Question 3

Who does lactational mastitis (infectious) affect?

Answer 3

10% of nursing mothers usually 2-4 weeks post-partum

Question 4

What is the most common causative agent of infective mastitis?

Answer 4

Staphylococcus aureus (coagulase-negative, gram-positive)

Question 5

What does non-infectious mastitis include?

Answer 5

Idiopathic granulomatous inflammation and other inflammatory conditions e.g. foreign body reaction (to piercing, breast implant, silicone) or underlying duct ectasia

Question 6

What is a breast abscess?

Answer 6

A localised area of infection with a walled-off collection of pus - main complication of mastitis

May or may not be associated with mastitis

Question 7

What is the biggest risk factor for breast abscess/mastitis?

Answer 7

Breastfeeding

Question 8

What are some non-puerperal abscesses unrelated to breastfeeding? (2)

Answer 8

• subareolar mastitis - damage to subareolar ducts –> infection (smoking = risk factor)
• peripheral mastitis - caused by systemic diseases, DM/corticosteroid use may contribute
  
  • lactational abscess often peripheral and due to cracking of nipple –> entrance of bacteria that infect milk-filled ducts

Question 9

What is TB of the breast?

Answer 9

• nodular, diffuse sclerosing reaction
• most common presentation - painless bump +/- sinus tract
• most cases secondary and infection occurs via contagious spread from lymphatics (commonly axillary, followed by cervical/mediastinal nodes)

Question 10

What is the main complication of mastitis?

Answer 10

Breast abscess

Question 11

What are the clinical features of mastitis? (4)

Answer 11

• tender, firm, swollen, erythematous, warm breast
• pain during breastfeeding (sharp) + decreased milk outflow
• flu-like symptoms: fever, malaise, myalgia
• nipple discharge - purulent discharge associated with infection

Question 12

What does a breast abscess look like?

Answer 12

Fluctuant, tender mass with overlying erythema

Question 13

What might you see on examination of breast abscess/mastitis? (5)

Answer 13

• breast mass - localised mastitis or breast abscess
• fistula - often with draining sinus
• nipple inversion/retraction
• lymphadenopathy - tender axillary LNs
• extra-mammary skin lesions (systemic)

Question 14

What are the main risk factors for breast abscess/mastitis? (11)

Answer 14

• lactation
• female sex
• women >30
• poor breastfeeding technique
• milk stasis
• nipple injury
• previous mastitis
• prolonged mastitis (breast abscess)
• previous breast abscess
• skin infection
• S. aureus carrier

Question 15

What are the first-line investigations for breast abscess/mastitis? (4)

Answer 15

• breast ultrasound
• diagnostic needle aspiration drainage
• cytology of nipple discharge or sample from fine-needle aspiration
• milk, aspirate, discharge or biopsy tissue for culture and sensitivity

Question 16

What scan can we do for breast abscess/mastitis?

Answer 16

Breast US - shows pus collection; hypoechoic lesion shows abscess

Question 17

What more invasive diagnostic techniques are there for breast abscess/mastitis? (2)

Answer 17

• diagnostic needle aspiration drainage - purulent fluid indicates breast abscess
• fine-needle aspiration - for cytology

Question 18

How can we identify the causative agent for breast abscess/mastitis?

Answer 18

Breast milk cultures and sensitivity

Question 19

What are some differential diagnoses for breast abscess/mastitis? (6)

Answer 19

• breast engorgement (3rd day post-partum, relieved by breastfeeding)
• nipple sensitivity
• galactocoele (milk retention may cause lump)
• fibrocystic breasts
• primary invasive breast cancer (hard, irregular, painless mass +/- fixed to underlying tissue)
• fibroadenoma (non-tender, rubbery, well-circumscribed and mobile mass)

Question 20

What is the first-line management for uncomplicated mastitis?

Answer 20

Continue breastfeeding (milk removal) - alternate breasts every few hours + analgesia (e.g. ibuprofen)

Question 21

How do we manage mastitis with infection/not improving after 12-24h despite effective milk removal?

Answer 21

Empirical Abx treatment:

Flucloxacillin 10d first-line for lactational (S. aureus most common)

Co-amoxiclav 10-14d first-line for non-lactational

Further Abx guided by cultures, MRSA –> clindamycin or co-trimoxazole

Question 22

How do we manage a breast abscess?

Answer 22

Surgical intervention - needle aspiration, incision and drainage (with local anaesthesia) +/- USS guidance

Question 23

How do we manage a persistent breast abscess?

Answer 23

Consider excising chronically infected tissue and major lactiferous duct associated with abscess

Question 24

What are some complications of breast abscess/mastitis? (10)

Answer 24

• recurrence
• cessation of breastfeeding
• mastitis –> abscess
• sepsis
• scarring
• fistula
• functional mastectomy
• breast hypoplasia
• necrotising fasciitis
• extra-mammary skin infection

Question 25

Describe the prognosis of breast abscess/mastitis.

Answer 25

• when promptly treated, most breast infections including abscess will resolve without serious complications
• resolution of mastitis after 2-3 days of appropriate Abx therapy is expected in most patients