What are the diagnosis and treatment options for mastitis in men on an outpatient basis?

Mastitis in Men: Diagnosis and Treatment

Critical First Step: Rule Out Malignancy

True mastitis in men is exceedingly rare, and any presentation of unilateral breast inflammation, pain, or mass requires immediate evaluation to exclude male breast cancer, which accounts for <1% of all breast cancers but has a median age of 63 years. 1

The term "mastitis" in men is often a misnomer—what appears as breast inflammation is more commonly gynecomastia (which can be painful), pseudogynecomastia, or rarely, inflammatory breast cancer masquerading as infection. 1

Diagnostic Algorithm

Step 1: Clinical Assessment

Physical examination findings that distinguish benign from concerning pathology:

• Gynecomastia characteristics: Soft, rubbery, or firm mobile mass directly under the nipple, often bilateral (50% of cases), and painful especially when present <6 months 1
• Red flags requiring urgent imaging: Unilateral presentation, hard or fixed mass, eccentric location (not subareolar), nipple retraction, bloody nipple discharge, skin changes (peau d'orange), or axillary adenopathy 2, 1, 3
• Inflammatory breast cancer warning signs: Erythema occupying ≥1/3 of breast surface, peau d'orange, symptoms persisting >1 week despite antibiotics 3

Step 2: Imaging Decision Tree

For men with clear clinical gynecomastia or pseudogynecomastia, no imaging is routinely recommended. 1 However, if differentiation between benign disease and breast cancer cannot be made clinically, proceed with imaging:

• Men <25 years: Ultrasound is the initial imaging study 2, 1
• Men ≥25 years: Diagnostic mammography or digital breast tomosynthesis (DBT) is recommended as the initial study (sensitivity 92-100%, specificity 90-96%, negative predictive value 99-100%) 2, 1
• If mammography shows indeterminate or suspicious findings: Follow with ultrasound breast imaging 2

Step 3: Tissue Diagnosis When Indicated

If imaging reveals suspicious features, core needle biopsy is superior to fine-needle aspiration for sensitivity, specificity, and correct histological grading. 1

• Ultrasound-guided core biopsy is preferred for lesions visible on ultrasound due to real-time visualization, patient comfort, and absence of radiation 1
• Stereotactic-guided biopsy for lesions only visible on mammography 1
• Place a marker clip post-biopsy to document sampling and aid future correlation 1

Treatment Approach for True Mastitis in Men

If Infectious Mastitis is Confirmed (Rare in Men)

Empiric antibiotic therapy targeting Staphylococcus aureus is the cornerstone of treatment:

• First-line antibiotics: Dicloxacillin or cephalexin 3, 4
• Supportive care: NSAIDs and ice application 3
• Duration: Continue until clinical resolution, typically 10-14 days 4

As methicillin-resistant S. aureus becomes more prevalent, consider antibiotics effective against MRSA if initial therapy fails or in high-risk populations. 4

Monitoring for Complications

Approximately 10% of mastitis cases progress to breast abscess. 3

• Perform ultrasound if symptoms worsen or recur despite appropriate antibiotics 3
• If abscess forms: Surgical drainage or needle aspiration is required 3, 4

If Inflammatory Signs Persist >1 Week

Symptoms not responding to appropriate antibiotics within 1 week mandate urgent re-evaluation for inflammatory breast cancer. 3

• Perform urgent ultrasound to identify mass or abscess 3
• If mass detected, obtain core needle biopsy within 48 hours 3
• Consider punch biopsy of skin if inflammatory breast cancer suspected 3
• Arrange multidisciplinary oncology referral within 24-48 hours 3

Common Pitfalls to Avoid

• Do not delay antibiotic therapy in men with clear inflammatory signs, as non-lactational mastitis is more likely infectious from the outset 3
• Do not assume all breast pain is mastitis—differential includes Mondor disease, costochondritis, chest wall pain, trauma, and rarely inflammatory breast cancer 3
• Do not order unnecessary imaging in clear cases of gynecomastia, as this leads to additional unnecessary benign biopsies 1
• Do not miss inflammatory breast cancer—delay in recognition significantly worsens mortality 3

When to Refer

• Endocrinology referral: Men with elevated baseline estradiol measurements to determine underlying hormonal causes 1
• Oncology referral (urgent): Any suspicion for inflammatory breast cancer or biopsy-proven malignancy 3
• Surgery referral: Abscess formation requiring drainage, or consideration of excision for recurrent inflammatory conditions 3, 5