New Surgical Guidelines for the Management of Mastitis (Mitchell et al., JAMA Surgery 2026)

This publication represents the second volume of the guidelines from the American Society of Breast Surgeons, the Society of Breast Imaging, and the College of American Pathology on the management of benign breast diseases and addresses infectious and inflammatory breast conditions during breastfeeding: lactational mastitis (LM), granulomatous mastitis (GM), and periductal mastitis with squamous metaplasia of the lactiferous ducts* (PDM-SMOLD).

*Squamous metaplasia is a benign (non-cancerous) modification that occurs when normal cells of a tissue or organ are replaced by specialized cells called squamous cells. This type of change occurs as an adaptive response to repeated irritations or inflammations of the tissues. Squamous metaplasia often occurs in the respiratory tract, urinary tract (especially the bladder), and cervix.

The authors first propose care consisting of the application of cold, avoidance of too frequent breast drainage, non-steroidal anti-inflammatory drugs (NSAIDs), and analgesics.

Breast massages should be strictly avoided as they can lead to lesions leading to infectious mastitis, phlegmon, or abscess.

Too many pumping sessions and nursing sessions can also lead to milk overproduction and aggravate symptoms and are not recommended. Most non-infectious mastitis resolves with these measures, provided there has been no vigorous massage, within a few days to one week.

Infectious mastitis can occur in case of heat application, vigorous massage, and excessive pumping. Immediate antibiotic treatment should be avoided as spontaneous resolution is possible; it is recommended to wait 24-48 hours unless the patient has frank cellulitis.

Cellulitis is an acute bacterial infection of the skin and subcutaneous tissues, most often caused by streptococci or more rarely by staphylococci. The symptomatology consists of pain, heat, erythema that spreads rapidly, and edema.

If antibiotics are necessary, the protocol indicates to continue breastfeeding and to prescribe Dicloxacillin 500 mg orally 4 times a day for 10 days as a first-line treatment. Cephalexin 50 mg 4 times a day for 10 days can be used for broader coverage. In case of allergy or MRSA, clindamycin 300 mg 4 times a day orally or trimethoprim-sulfamethoxazole DS 2 times a day orally is recommended. Hot compresses can aggravate inflammation and infection and are not recommended.

Abscess:

The authors discuss ultrasound-guided aspirations, indicating that syringe aspirations are ineffective because the fluids are very viscous and aspiration is often suboptimal, requiring multiple procedures with a risk of spontaneous drainage. The recommendations are therefore to perform surgical drainage with incision and placement of a drain, as far as possible from the areola-nipple complex. A fluid culture should be performed, and milk discharge through the incision is expected and normal after drain removal. It is recommended to pump and breastfeed according to the baby's needs, avoiding pumping if it interferes with the drainage site. It is advised not to touch the drainage site (e.g., trying to empty it by pressing). Medications to reduce lactation (cabergoline) are mentioned. In France, these medications have marketing authorization for lactation suppression in pathological situations.

Granulomatous Mastitis

Granulomatous Mastitis (GM) The diagnosis relies absolutely on a core biopsy confirming non-caseating granulomas, thus excluding cancer, as the clinical presentation often resembles a classic infectious abscess. The specific form related to Corynebacterium (cystic neutrophilic granulomatous mastitis) must be treated empirically with doxycycline, while the idiopathic form does not justify antibiotics without bacterial proof. Management favors intra-lesional steroid injections (triamcinolone) after aspiration, avoiding invasive surgeries that can cause cosmetic deformities. Refractory cases may require oral corticosteroids or immunosuppressants like methotrexate, often in collaboration with a rheumatologist. The disease is chronic and recurrent, taking up to 18 months to resolve, requiring close follow-up until imaging normalizes. Surgical excision and mastectomy are considered last resorts in case of failure of all medical treatments.

Periductal Mastitis with Squamous Metaplasia of Lactiferous Ducts

Periductal Mastitis with Squamous Metaplasia (PDM-SMOLD). Also known as Zuska's disease, this distinct condition involves obstruction of the lactiferous ducts by squamous metaplasia, leading to recurrent abscesses and fistulas. Initial treatment includes antibiotics covering S. aureus and anaerobes, as well as smoking cessation and removal of breast piercings to reduce inflammation. Ultrasound-guided aspiration is recommended for abscesses, but surgical excision is required in case of persistent fistula or frequent recurrences. Definitive surgical intervention consists of radial excision of the diseased ducts under the nipple, simultaneously correcting any cleft or nipple inversion, and must be performed during an inflammatory remission period. Duct irrigation is not recommended as first-line treatment due to inferior results compared to targeted excision. The prognosis is good after complete resection, but recurrence is high if diseased ducts are not totally removed.

Bibliography Mitchell, K. B., et al. (2026). American Society of Breast Surgeons, Society of Breast Imaging, and College of American Pathology 2025 Guidelines for the Management of Infectious and Inflammatory Lesions of the Breast. JAMA Surgery.