Mastitis: what is it, causes, symptoms, treatment, prognosis

What is mastitis?

Mastitis Is an inflammation of the breast tissue. Mastitis can be divided into lactational and non-lactational. Lactational mastitis is the most common form of the disease. The two types of non-lactational mastitis include periductal and idiopathic granulomatous mastitis (IGM). The disease is also acute, less often chronic.

Lactational mastitis, also known as postpartum mastitis, usually results from prolonged engorgement of the milk ducts with infectious components due to bacteria entering through skin tears. Patients develop focal erythema, pain and edemaand there may also be associated systemic symptoms, including fever. The disease most often occurs in the first six weeks of breastfeeding, but can occur at any time during lactation, and in most cases after 3 months.

Periductal mastitis is a benign inflammatory disease that affects the subareolar ducts and is most common in women of reproductive age. Idiopathic granulomatous mastitis is a rare and benign inflammatory disorder that can clinically mimic breast cancer. The disease occurs mainly in women who have given birth, most often within 5 years after childbirth.

Signs and symptoms

Lactational mastitis is often preceded by engorgement or focal blockage of the duct. Patients may present with a history of these accompanying symptoms before the classic signs of mastitis develop. Lactational mastitis is characterized by a focal, hard, erythematous, swollen and painful area of ​​the breast, and fever (greater than or equal to 38 degrees Celsius). Patients often experience systemic symptoms such as chills, myalgias, and malaise.

Signs of periductal mastitis include a periareolar or subareolar mass, which may be associated with pain and erythema. Patients may have nipple curls, thick nipple discharge, abscess breasts or draining fistulas.

IHI most often presents with a hard, unilateral breast mass. Other signs may include nipple retraction, skin thickening, axillary adenopathy, ulceration, and abscess formation. Many of these signs overlap with those of breast cancer, and sometimes the disease can be misdiagnosed at an early stage. Patients with IHI may also experience extra-mammary manifestations, including arthralgia, episcleritis and skin changes.

Causes and risk factors

Lactational mastitis is most commonly caused by bacteria that colonize the skin, with the most common being Staphylococcus aureus (Staphylococcus aureus). Methicillin-resistant Staphylococcus aureus (MRSA) is an increasingly common cause of mastitis, and risk factors for MRSA should be considered. Other pathogens include Streptococcus pyogenes,Escherichia coli, views Bacteroides and coagulase-negative staphylococci. Risk factors for lactational disease include:

• a history of mastitis;
• cracked nipples;
• insufficient outflow of milk;
• stress in the mother;
• lack of sleep;
• wearing tight-fitting bras;
• using antifungal nipple creams.

The cause of periductal mastitis is not clear. However, many speculate that smoking may be associated with the development of the disease due to direct damage to the ducts and subsequent inflammation. The bacteria are cultured in 62–85% of patients with periductal mastitis, and the most common pathogens include Staphylococcus aureus, Pseudomonas aeruginosa, Enterococcus, Bacteroides and Proteus. Obesity and diabetes are also possible risk factors.

The etiology of idiopathic granulomatous mastitis (IGM) remains unclear. Possible reasons were:

• autoimmune diseases;
• trauma;
• lactation period;
• taking oral contraceptives;
• hyperprolactinemia.

There may also be an association with Corynebacterium (corynebacterium), especially in patients with histological signs of cystic neutrophilic granulomatous mastitis (CNGM).

Epidemiology

Worldwide, lactational mastitis occurs in 2-30% of breastfeeding women. The incidence is highest in the first three weeks after delivery.

Patients with periductal mastitis are most often women of reproductive age and are almost exclusively associated with tobacco use. Periductal mastitis occurs in 5–9% of women worldwide.

HMI is very rare and its true prevalence is unknown. BMI occurs in women who have given birth, as a rule, within five years after childbirth. Most patients report a history of breastfeeding and develop symptoms from six months to two years after stopping breastfeeding. The average age of debut is from 32 to 34 years old. Several studies have shown a higher incidence of IHI among the Hispanic population.

Pathophysiology

Lactational mastitis occurs due to insufficient milk outflow and the penetration of bacteria. Common scenarios that lead to poor milk flow include infrequent feeding, too much milk, rapid weaning, mother or baby illness, and blockage of the duct. Improperly drained milk stagnates and organisms (bacteria) multiply, leading to infection. It is believed that bacteria (usually from a baby's mouth or mother's skin) enter milk through cracks in the nipple.

The pathophysiology of periductal mastitis remains unclear. Smoking is believed to play a role in pathogenesis, directly or indirectly damaging the ducts, leading to subsequent necrosis and infection. Squamous cell metaplasia is common in patients with this disorder, and it is believed that desquamated metaplastic cells can form a plug leading to a blockage of the duct and subsequent infections. One recent study showed that a group of patients with periductal mastitis has an upregulated IFN-γ γ and IL-12A compared to control. These are cytokines secreted by TH1 cells and they play a role in killing foreign pathogens. The upregulation of these cytokines suggests that immune responses may play a role in the pathogenesis of periductal mastitis.

The pathophysiology of IHI remains unclear, but the most widespread theory points to autoimmune destruction initiated by a specific trigger such as trauma, bacteria, or extravasated milk. This causes the secretion to leak from the ducts into the breast tissue, and the inflammatory cells infiltrate and induce a granulomatous response.

Histopathology

Idiopathic granulomatous mastitis (IGM) is characterized by noncaseating granulomas with epithelioid histiocytes and multinucleated giant cells in the lobes of the breast. In the KNGM subtype, the classic histological features are noncaseating granulomas with characteristic cystic spaces lined with neutrophils containing gram-positive cocci. It is important to note that biopsy is generally not recommended for evaluating periductal or lactational mastitis.

Diagnostics

The diagnosis of lactational mastitis is based on history and clinical findings. If there is concern that the patient may have a breast abscess, an ultrasound scan of the breast is performed. If present abscess, hypoechoic areas of purulent material will be visible. For patients with severe infection who do not respond to initial antibiotic therapy, breast milk culture may be helpful in determining the correct antibiotic choice. However, this is usually not necessary. Likewise, if there are concerns about bacteremia in a patient with severe illness, a blood culture should be done. However, this is not part of daily practice.

Periductal mastitis is primarily a clinical diagnosis. If nipple drainage is present, Gram stain and culture should be done to identify any associated organisms. If there is an associated formation and there is concern about a malignant neoplasm, ultrasound or mammography should be performed.

Since the clinical signs of IHI overlap with the clinical signs of breast cancer, a biopsy is necessary to make this diagnosis. Puncture biopsy or excisional biopsy options are available. Because of the putative link between hyperprolactinemia and IHI, prolactin levels can be monitored. Ultrasound and mammography do not distinguish IHM from breast cancer.

Treatment

The initial treatment for lactational mastitis is symptomatic. Continued complete breast emptying showed a decrease in the duration of symptoms in patients treated with and without antibiotics. Patients should be encouraged to continue breastfeeding or expressing milk. If the patient stops draining milk, further stagnation occurs and the infection progresses. Non-steroidal anti-inflammatory drugs (NSAIDs) can be used to relieve pain. Heat applied to the breast just prior to emptying can help increase milk flow and make emptying easier. Cold compresses applied to the chest after a bowel movement can help reduce swelling and pain.

If symptoms of lactation mastitis persist for more than 12-24 hours, antibiotics should be prescribed. Because the S. aureus is the most common reason, and antibiotic therapy should be selected accordingly. In mild infections without MRSA risk factors, outpatient treatment can be started with dicloxacillin or cephalexin. If the patient is allergic to penicillin, erythromycin can be used. If the patient has risk factors for MRSA infection, treatment options include trimethoprim-sulfamethoxazole (co-trimoxazole) or clindamycin. Co-trimoxazole should be avoided in women who are breastfeeding infants less than 1 month of age and in infants with jaundice or premature babies. If the patient requires hospitalization, empiric treatment with vancomycin should be initiated until culture and sensitivity return. There is not enough research on the appropriate duration of outpatient treatment, but most sources recommend a 10-14 day course.

Periductal mastitis is treated empirically with amoxicillin-clavulanate. Alternatives include dicloxacillin plus metronidazole or cephalexin plus metronidazole. In the presence of an abscess, the preferred treatment strategy is ultrasound-guided aspiration puncture in combination with antibiotic therapy. The periductal form of the disease is often a recurring disease. If the patient has recurrent infections, surgical removal of the inflamed ducts may be necessary.

The treatment of IHI remains controversial. Current treatment strategies vary widely and may include surveillance, corticosteroids, immunosuppressants, antibiotics, and surgery. IHI is a benign disease that usually goes away without treatment on average within 5 months. A recent study showed that the time until symptoms disappear did not differ between patients who have been treated with drugs, and in patients treated with supervision and supportive care therapy. Alternatively, surgical removal is used, but a 10% relapse has been reported even with surgical treatment. If IHI is complicated by secondary infection, antibiotics should be selected on the basis of culture and susceptibility.

Forecast

Most women with mastitis recover with appropriate treatment. The recurrence rate for each type of mastitis varies as follows:

• Lactation: 8-30%
• Periductal: 4-28%
• Idiopathic granulomatous: 20–78%

One study found that 38% of patients with IHI reported significant scarring and 29% reported prolonged pain.

Complications

One of the most common complications of lactational mastitis is early termination of breastfeeding. Breast disease and associated pain are some of the most frequently cited reasons for premature breastfeeding termination. Breast abscess is another complication of lactational mastitis and occurs in 3–11% of patients. Breast abscess development is more common if mastitis is not treated early.

Both periductal mastitis and IHI can be complicated by the formation of an abscess or fistula. Both forms of non-lactational disease are associated with relapse and can lead to scarring and deformation of breast tissue.