Mastitis
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Basics
Description
- Mastitis is an inflammation of the breast parenchyma and possibly associated tissues (areola, nipple, subcutaneous [SC] fat).
- Usually associated with bacterial infection (and milk stasis in the postpartum mother)
- Usually an acute condition but can become chronic cystic mastitis
Epidemiology
- Predominantly affects females
- Mostly in the puerperium; epidemic form rare in the age of reduced hospital stays for mothers and newborns
- Neonatal form
- Posttraumatic: ornamental nipple piercing increases risk of transmission of bacteria to deeper breast structures: Staphylococcus aureus is the predominant organism.
Incidence
- 3–20% of breastfeeding mothers develop nonepidemic mastitis.
- Greatest incidence among breastfeeding mothers 2 to 6 weeks postpartum
- Neonatal form occurs at 1 to 5 weeks of age, with equal gender risk and unilateral presentation.
- Pediatric form
- Around or after puberty
- 82% of cases in girls
Etiology and Pathophysiology
- Microabscesses along milk ducts and surrounding tissues
- Inflammatory cell infiltration of breast parenchyma and surrounding tissues
- Nonpuerperal (infectious)
- S. aureus, Bacteroides sp., Peptostreptococcus, Staphylococcus (coagulase neg.), Enterococcus faecalis
- Histoplasma capsulatum
- Salmonella enterica
- Rare case of Actinomyces europaeus
- Puerperal (infectious)
- Staphylococcus aureus, Streptococcus pyogenes (group A or B), Corynebacterium sp., Bacteroides sp., Staphylococcus (coagulase neg.), Escherichia coli, Salmonella sp.
- Methicillin-resistant S. aureus (MRSA)
- Rare secondary site for tuberculosis in endemic areas (1% of mastitis cases in these areas): single breast nodule with mastalgia
- Tuberculosis mastitis in non-endemic areas has also been reported in patients with exposure to TNF-alpha inhibitors and other immunomodulating compounds (1)[C].
- Corynebacterium sp. associated with greater risk for development of chronic cystic mastitis
- Granulomatous mastitis
- Idiopathic
- Predilection for Asian and Hispanic women
- Association with α1-antitrypsin deficiency, hyperprolactinemia with galactorrhea, oral contraceptive use, Corynebacterium sp. infection, and breast trauma
- Most women have a history of lactation in previous 5 years.
- New cases have been reported in male-to-female transgender patients in setting of exogenous progesterone and estrogen treatment (2)[B].
- Lupus; autoimmune
- Idiopathic
- Puerperal
- Retrograde migration of surface bacteria up milk ducts
- Bacterial migration from nipple fissures to breast lymphatics
- Secondary monilial infection in the face of recurrent mastitis or diabetes
- Seeding from mother to neonate in cyclical fashion
- Nonpuerperal
- Ductal ectasia
- Breast carcinoma
- Inflammatory cysts
- Chronic recurring SC or subareolar infections
- Parasitic infections: Echinococcus; filariasis; Guinea worm in endemic areas
- Herpes simplex
- Cat-scratch disease
- Lupus
Risk Factors
- Breastfeeding
- Milk stasis
- Inadequate emptying of breast
- Scarring of breast due to prior mastitis
- Scarring due to previous breast surgery (breast reduction, biopsy, or partial mastectomy)
- Breast engorgement: interruption of breastfeeding
- Inadequate emptying of breast
- Nipple trauma increases risk of transmission of bacteria to deeper breast structures: S. aureus predominant organism
- Neonatal colonization with epidemic Staphylococcus
- Neonatal
- Bottle-fed babies
- Manual expression of “witch’s milk”
- Can predispose to lethal necrotizing fasciitis
- Maternal diabetes
- Maternal HIV
- Maternal vitamin A deficiency (in animal models)
- Smoking
General Prevention
Regular emptying of both breasts and nipple care to prevent fissures when breastfeeding; also good hygiene including hand washing and washing breast pumps after each use
Commonly Associated Conditions
Breast abscess
-- To view the remaining sections of this topic, please log in or purchase a subscription --
Basics
Description
- Mastitis is an inflammation of the breast parenchyma and possibly associated tissues (areola, nipple, subcutaneous [SC] fat).
- Usually associated with bacterial infection (and milk stasis in the postpartum mother)
- Usually an acute condition but can become chronic cystic mastitis
Epidemiology
- Predominantly affects females
- Mostly in the puerperium; epidemic form rare in the age of reduced hospital stays for mothers and newborns
- Neonatal form
- Posttraumatic: ornamental nipple piercing increases risk of transmission of bacteria to deeper breast structures: Staphylococcus aureus is the predominant organism.
Incidence
- 3–20% of breastfeeding mothers develop nonepidemic mastitis.
- Greatest incidence among breastfeeding mothers 2 to 6 weeks postpartum
- Neonatal form occurs at 1 to 5 weeks of age, with equal gender risk and unilateral presentation.
- Pediatric form
- Around or after puberty
- 82% of cases in girls
Etiology and Pathophysiology
- Microabscesses along milk ducts and surrounding tissues
- Inflammatory cell infiltration of breast parenchyma and surrounding tissues
- Nonpuerperal (infectious)
- S. aureus, Bacteroides sp., Peptostreptococcus, Staphylococcus (coagulase neg.), Enterococcus faecalis
- Histoplasma capsulatum
- Salmonella enterica
- Rare case of Actinomyces europaeus
- Puerperal (infectious)
- Staphylococcus aureus, Streptococcus pyogenes (group A or B), Corynebacterium sp., Bacteroides sp., Staphylococcus (coagulase neg.), Escherichia coli, Salmonella sp.
- Methicillin-resistant S. aureus (MRSA)
- Rare secondary site for tuberculosis in endemic areas (1% of mastitis cases in these areas): single breast nodule with mastalgia
- Tuberculosis mastitis in non-endemic areas has also been reported in patients with exposure to TNF-alpha inhibitors and other immunomodulating compounds (1)[C].
- Corynebacterium sp. associated with greater risk for development of chronic cystic mastitis
- Granulomatous mastitis
- Idiopathic
- Predilection for Asian and Hispanic women
- Association with α1-antitrypsin deficiency, hyperprolactinemia with galactorrhea, oral contraceptive use, Corynebacterium sp. infection, and breast trauma
- Most women have a history of lactation in previous 5 years.
- New cases have been reported in male-to-female transgender patients in setting of exogenous progesterone and estrogen treatment (2)[B].
- Lupus; autoimmune
- Idiopathic
- Puerperal
- Retrograde migration of surface bacteria up milk ducts
- Bacterial migration from nipple fissures to breast lymphatics
- Secondary monilial infection in the face of recurrent mastitis or diabetes
- Seeding from mother to neonate in cyclical fashion
- Nonpuerperal
- Ductal ectasia
- Breast carcinoma
- Inflammatory cysts
- Chronic recurring SC or subareolar infections
- Parasitic infections: Echinococcus; filariasis; Guinea worm in endemic areas
- Herpes simplex
- Cat-scratch disease
- Lupus
Risk Factors
- Breastfeeding
- Milk stasis
- Inadequate emptying of breast
- Scarring of breast due to prior mastitis
- Scarring due to previous breast surgery (breast reduction, biopsy, or partial mastectomy)
- Breast engorgement: interruption of breastfeeding
- Inadequate emptying of breast
- Nipple trauma increases risk of transmission of bacteria to deeper breast structures: S. aureus predominant organism
- Neonatal colonization with epidemic Staphylococcus
- Neonatal
- Bottle-fed babies
- Manual expression of “witch’s milk”
- Can predispose to lethal necrotizing fasciitis
- Maternal diabetes
- Maternal HIV
- Maternal vitamin A deficiency (in animal models)
- Smoking
General Prevention
Regular emptying of both breasts and nipple care to prevent fissures when breastfeeding; also good hygiene including hand washing and washing breast pumps after each use
Commonly Associated Conditions
Breast abscess
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