Mastitis: Clinical sciences

Mastitis is a benign breast condition that involves ductal or periductal inflammation, which can lead to secondary infection of the breast tissue. Mastitis is frequently associated with lactation, but can affect both lactating and non-lactating patients. During lactation, reduced milk drainage can lead to bacterial overgrowth and secondary infection. On the flip side, the exact causes of non-lactational mastitis are not well understood. Non-lactating patients with recurrent mastitis should be evaluated for a rare form of the disease called granulomatous mastitis.

Alright, so when assessing a patient with a chief concern suggestive of mastitis, the first step is to obtain a focused history and physical exam, and labs such as a CBC.

Let’s say a patient presents who is currently lactating. They might report a history of incomplete emptying of breast milk, either from difficult or infrequent breastfeeding or perhaps from a blocked duct and engorgement. They may also report mastalgia and malaise.

On physical exam, you might discover breast fullness, erythema, induration, and tenderness. Additionally, you may see nipple fissures or skin breaks, and the patient might even have a fever. Finally on labs, the CBC may even show a leukocytosis. If this is the case, go ahead and diagnose puerperal mastitis.

Here’s a clinical pearl! Remember that the puerperium is a period of about 6 weeks, right after childbirth, during which the patient’s body undergoes changes to return to their original state before the pregnancy, such as uterine involution with the uterus shrinking back to its normal size.

Now that we have made a diagnosis, let’s talk about management. Start with antibiotics. Here, you want to cover common skin flora, especially Staphylococcus aureus. Since the patient is breastfeeding, be sure to use antibiotics that are safe for the baby as they might get released in the milk. Now, you also need to consider covering for MRSA, which depends on the severity of the infection as well as the presence of risk factors such as known colonization or recent hospitalization.

Dicloxacillin or cephalexin are common choices for mild infections and no MRSA risk factors. For patients at risk for MRSA, trimethoprim-sulfamethoxazole can be prescribed, as long as the breastfeeding child is healthy and at least one month of age, since this antibiotic increases the neonate’s risk of developing hyperbilirubinemia and complications like kernicterus.

Alright, in addition to treating the infection, you want to give symptomatic treatment to make the patient comfortable. For this, you can prescribe some common pain medications like ibuprofen or acetaminophen. Other helpful treatments include cold or warm compresses on the affected breast.

Make sure that the patient continues effective milk emptying through breastfeeding, manual expression, or pumping. Encourage the patient and provide any counseling or instruction necessary to promote successful attachment and feeding. Finally, follow-up within two to three days, in order to assess the patient’s response to antibiotics and to monitor for improvement in symptoms.

Okay, now that the treatment has started, let’s talk about the response. Patients with an adequate response to treatment will report symptom improvement on the follow-up exam. If this is the case, go ahead and continue the treatment plan. On the flip side, some patients might show inadequate response to treatment, meaning that their symptoms didn’t improve, or even got worse. In this case, suspect puerperal mastitis with abscess.

Okay, since you are suspecting an abscess, you’ll need to order some imaging, like a breast ultrasound. Let’s say the breast ultrasound shows soft tissue edema but no fluid collection suggestive of an abscess. If this is the case, broaden antibiotic selection to cover MRSA, continue supportive care, and follow up with the patient to make sure that they are responding to the new treatment plan.

Now, let’s return to the ultrasound results to consider other options. If you see a hypoechoic fluid collection in the breast, with or without loculations, diagnose puerperal mastitis with abscess. Aspirate the fluid collection under ultrasound guidance, and send the fluid for gram stain and culture. Next, change to antibiotics that cover MRSA, and tailor the antibiotic coverage when you get the microbiology studies back, if possible. Otherwise, continue pain control and effective milk emptying. Finally, be sure to follow up in a couple of days.

Alright, let’s go all the way back to the history and physical and talk about non-lactating patients who present with signs and symptoms of mastitis. These patients might report mastalgia, breast swelling or redness, or even nipple discharge. You might also find some risk factors for mastitis in their history, like the use of tobacco products, diabetes, or obesity. Make sure to ask about any history of breast or thoracic radiation, as well as former diagnoses of ductal ectasia or periductal mastitis.

When it comes to the physical exam, it might reveal breast erythema, induration, and tenderness to palpation. Nipple retraction or purulent nipple discharge may be present, as well as a fluctuant mass or draining periareolar fistula. The patient may even have an elevated temperature. Lastly, labs typically show leukocytosis.