Management of Male Unilateral Mastitis
Male unilateral mastitis requires immediate imaging to exclude malignancy, followed by tissue diagnosis if suspicious features are present, because breast cancer in men—though rare—typically presents unilaterally and must be ruled out before attributing symptoms to benign inflammatory conditions.
Initial Diagnostic Approach
Age-Based Imaging Algorithm
For men 25 years and older presenting with unilateral breast inflammation or mass, obtain bilateral mammography or digital breast tomosynthesis (DBT) as the first-line imaging study, as this modality demonstrates 92-100% sensitivity, 90-96% specificity, and 99-100% negative predictive value for distinguishing benign from malignant disease 1, 2.
For men younger than 25 years, start with ultrasound as the initial imaging modality due to the extremely low incidence of breast cancer in this age group; if ultrasound reveals suspicious or indeterminate features, proceed to mammography or DBT before considering biopsy 1, 3.
Bilateral mammography should be performed routinely to assess for symmetry and detect possible contralateral abnormalities, even when symptoms are unilateral 1, 2.
Critical Clinical Distinction
Do not assume gynecomastia when presentation is unilateral, inflammatory, or associated with a hard, fixed, or eccentric mass, as the American College of Radiology emphasizes that relatively benign imaging findings should be considered suspicious in male patients due to different breast anatomy 1, 3.
Imaging is mandatory when clinical differentiation between benign disease and breast cancer cannot be made, or when red flags are present including bloody nipple discharge, skin or nipple retraction, or unilateral fixed masses 3.
Tissue Diagnosis When Indicated
Biopsy Technique
If diagnostic mammography assigns a BI-RADS category 4 or 5 (suspicious or highly suggestive of malignancy), perform ultrasound-guided core needle biopsy, which is superior to fine-needle aspiration in terms of sensitivity, specificity, and correct histological grading 1, 2.
Ultrasound guidance is preferred for core needle biopsy due to patient comfort, real-time visualization of the needle, absence of ionizing radiation, and superior sampling accuracy 1, 2.
Always perform imaging before biopsy, as post-biopsy changes may confuse image interpretation 1.
Differential Diagnosis and Specific Management
Granulomatous Mastitis
Granulomatous mastitis (including idiopathic granulomatous mastitis and tuberculous mastitis) can mimic breast cancer in male patients, presenting as a painful or painless mass with signs of inflammation 4, 5, 6.
Definitive diagnosis requires histopathological evaluation showing non-caseifying granulomas, often with microabscess formation; fine-needle aspiration cytology may be diagnostic but acid-fast bacilli are demonstrable in only 33% of tuberculous cases 5, 6.
For confirmed granulomatous mastitis, combination therapy with methotrexate and steroids has the lowest recurrence rate (4%), compared to drainage alone which has the highest recurrence rate at 65% 7.
Surgical excision with thorough removal of inflammatory tissue and negative margins is associated with low recurrence rates (13% for excision alone, 7% when combined with steroids), and most patients ultimately require surgery despite initial conservative management 7, 5.
Infectious Mastitis
True bacterial mastitis in males is exceedingly rare and typically occurs in specific contexts (immunocompromise, trauma, or underlying breast pathology); when suspected, obtain milk or abscess cultures to guide antibiotic therapy 8, 9.
If bacterial infection is confirmed, prescribe narrow-spectrum antibiotics covering common skin flora (Staphylococcus, Streptococcus)—flucloxacillin, cephalexin, or cefuroxime are first-line agents, while amoxicillin/clavulanate provides broader coverage 8, 9.
Ultrasound-guided aspiration is preferred over incision and drainage for breast abscesses when technically feasible, as it is less invasive and associated with better cosmetic outcomes 8.
Gynecomastia with Inflammation
If imaging and clinical features ultimately suggest gynecomastia with superimposed inflammation rather than true mastitis, measure serum estradiol and refer to endocrinology if elevated, as hormonal imbalances (testosterone deficiency, elevated estradiol, hyperprolactinemia) are common underlying causes 3.
For testosterone-deficient patients with persistent painful gynecomastia, consider selective estrogen receptor modulators after endocrine evaluation, particularly in those with low or low-normal LH levels 3.
Common Pitfalls to Avoid
Never skip imaging in male patients with unilateral breast symptoms, as the threshold for malignancy suspicion must be lower than in women due to the rarity of benign breast conditions in men and the typical late presentation of male breast cancer (median age 63 years) 1, 3.
Do not perform unnecessary imaging in clear bilateral gynecomastia, as this leads to additional unnecessary benign biopsies without improving outcomes 3.
Avoid drainage as sole therapy for granulomatous mastitis, given its 65% recurrence rate; definitive surgical excision or combination medical therapy is required 7, 5.
Do not attribute unilateral inflammatory breast symptoms to simple infection without tissue diagnosis, as granulomatous mastitis and even male breast cancer can present with inflammatory features mimicking infection 4, 5.