Nonpuerperal Mastitis

Nonpuerperal mastitis is inflammation of the breast in a woman who is not pregnant or breastfeeding, caused by infection or by noninfectious inflammation. Causes include periductal mastitis (smoking related), granulomatous lobular mastitis, tuberculosis, fungal infection, nipple piercing and skin conditions. It affects women aged 20 to 50 years and matters because it mimics inflammatory breast cancer, causes recurrent abscesses and needs different treatment from lactational mastitis.

• Risk factors: smoking, diabetes, nipple piercing, nipple retraction, previous breast surgery, HIV, tuberculosis exposure, hyperprolactinaemia, recent childbirth within 5 years (granulomatous).
• Inflammatory breast cancer must be excluded in every case.
• Failure to settle after 7 days of antibiotics needs biopsy.

Women have a painful red breast, a tender lump or mass, nipple discharge or retraction, fever and sometimes an abscess or fistula. The skin may be swollen with peau d'orange change.

• Periareolar redness, nipple retraction or discharge in periductal disease.
• Firm peripheral mass with skin ulceration and sinuses in granulomatous disease.
• Differential diagnosis: inflammatory breast cancer, periductal mastitis, idiopathic granulomatous mastitis, tuberculous mastitis, fungal infection, bacterial abscess, fat necrosis, mammary duct ectasia, sarcoidosis, foreign body reaction, cellulitis.
• Complications: recurrent abscess, fistula, breast deformity, scarring, persistent pain, delay in diagnosis of cancer, drug side effects from long steroid courses.

The approach is triple assessment (examination, imaging, biopsy) to exclude cancer and identify the cause.

• Examination of both breasts and axillae; temperature; measurement of the area.
• Ultrasound of the breast and axilla; mammography if age is 40 years or above and the woman can tolerate it; MRI for complex disease.
• Core needle biopsy for histology (granulomatous inflammation with or without microabscess), culture, Ziehl-Neelsen stain, Xpert MTB/RIF, fungal culture and Gram stain.
• Full blood count, C-reactive protein, glucose, HIV test, prolactin, chest X-ray; tuberculin or interferon gamma test if tuberculosis is suspected.

The principle is to confirm the cause by biopsy, treat infection with antibiotics, treat granulomatous disease with steroids or methotrexate, and drain abscesses.

• Supportive: stop smoking; analgesia; supportive bra; remove nipple jewellery; warm compresses; control diabetes; skin care for sinuses; no surgery during active inflammation unless an abscess is present.
• Pharmacological: bacterial infection: amoxicillin-clavulanate 625 mg oral 8-hourly for 7 to 10 days, or cefalexin 500 mg oral 6-hourly plus metronidazole 400 mg oral 8-hourly for 7 to 10 days; severe infection: ceftriaxone 2 g IV once daily plus metronidazole 500 mg IV 8-hourly until improved, then oral therapy to complete 10 to 14 days; idiopathic granulomatous mastitis (after infection and tuberculosis are excluded): prednisolone 0.5 mg/kg oral once daily (usually 30 to 40 mg) for 4 weeks, then tapered over 8 to 12 weeks, with methotrexate 7.5 mg oral once weekly increased to 15 mg weekly and folic acid 5 mg oral once weekly for steroid resistant or relapsing disease (specialist care); tuberculous mastitis: rifampicin 10 mg/kg (usual 600 mg) plus isoniazid 5 mg/kg (usual 300 mg) plus pyrazinamide 25 mg/kg (usual 1500 mg) plus ethambutol 15 mg/kg (usual 1200 mg) oral once daily for 2 months, then rifampicin plus isoniazid for 4 months, with pyridoxine 25 mg oral once daily; fungal infection: fluconazole 400 mg oral once daily for 6 weeks or longer; paracetamol 1 g oral 6-hourly (maximum 4 g in 24 hours).
• Procedures: ultrasound guided aspiration of abscess; incision and drainage with biopsy of the wall; core biopsy before steroids; wide local excision for localised granulomatous disease that fails medical therapy; excision of a fistula and affected ducts.
• Special groups: women with HIV and tuberculosis use dolutegravir 50 mg oral twice daily while on rifampicin and have a specialist review; women with diabetes have insulin and glucose control before steroids; women who are breastfeeding or pregnant avoid methotrexate; women planning pregnancy stop methotrexate 3 months before conception.
• Red flags: skin thickening with peau d'orange, hard fixed mass, no response to 7 days of antibiotics, axillary nodes that are hard, ulceration, bloody nipple discharge, weight loss with night sweats.
• Follow-up: review at 1 week; repeat ultrasound at 4 weeks; steroid taper review at each step; recurrence monitoring for 12 months; mammography and examination at 6 months and 12 months.