What is the treatment for cystic neutrophilic granulomatous mastitis?

Treatment of Cystic Neutrophilic Granulomatous Mastitis

The optimal treatment for cystic neutrophilic granulomatous mastitis (CNGM) includes prolonged antibiotic therapy specifically directed against Corynebacterium species, often combined with surgical intervention and/or steroid therapy. 1

Understanding CNGM

• CNGM is a rare subtype of granulomatous mastitis with a distinct histological pattern characterized by suppurative lipogranulomas composed of central lipid vacuoles rimmed by neutrophils and an outer cuff of epithelioid histiocytes 1
• The condition is strongly associated with Corynebacterium infection, particularly Corynebacterium kroppenstedtii 2
• CNGM typically occurs in reproductive-age women with a history of pregnancy and presents as a painful palpable breast mass 1

Diagnostic Approach

• Imaging findings are nonspecific and may include:
  • Mammographic findings: focal asymmetry, skin thickening, and irregular or oval masses 2
  • Sonographic findings: irregular mass, complex collection/abscess, dilated ducts with intraductal debris, axillary lymphadenopathy, and skin thickening with subcutaneous edema 2
• Definitive diagnosis requires histopathologic examination with attention to the characteristic pattern of suppurative lipogranulomas 1
• Gram stain may reveal sparse, rod-shaped, gram-positive bacilli within lipid vacuoles that can be easily missed 1
• Multiple Gram stains may be necessary as the yield increases with repeated examination 3
• Microbiological culture and potentially molecular analysis (such as 16S PCR) should be performed to identify the causative organism 2, 4

Treatment Algorithm

First-line Treatment:

1. Antimicrobial Therapy

   • Prolonged antibiotic therapy specifically directed against Corynebacterium species 1
   • Continue treatment beyond resolution of clinical symptoms to prevent recurrence 1
   • Antibiotics should be initiated before steroid therapy if abscesses are present 5

2. Surgical Management

   • Surgical excision is often necessary, especially for larger lesions or abscesses 4
   • Complete surgical excision may be required for definitive treatment 5

3. Steroid Therapy

   • Oral corticosteroids are effective in reducing inflammation 4, 5
   • Should be combined with surgical excision for optimal results 5

Alternative/Adjunctive Treatments:

• Anti-inflammatory medications may be used in combination with steroids 5
• Colchicine has shown effectiveness in some cases 5
• Methotrexate has been reported as successful in treating granulomatous mastitis 5

Important Clinical Considerations

• CNGM can mimic breast carcinoma clinically and radiologically, making accurate diagnosis crucial 1, 5
• There appears to be an association with endocrinopathies in some patients 3
• Early diagnosis is essential to offer appropriate treatment and avoid unnecessary interventions 1
• The histomorphology may evolve, initially presenting as palisaded granulomatous inflammation before developing the classic "cystic" pattern 3
• Recurrence rates can be up to 50% if treatment is inadequate or discontinued prematurely 5

Treatment Duration and Follow-up

• Antimicrobial therapy should be continued beyond the resolution of clinical symptoms 1
• Immunosuppressive therapy should be maintained until complete remission to reduce recurrence risk 5
• Regular follow-up is necessary to monitor for recurrence and adjust treatment as needed 4