What is the cause of and treatment for burning breast pain on one side in a pregnant woman?

Burning Breast Pain on One Side in Pregnancy

Unilateral burning breast pain in pregnancy is most commonly a benign physiologic response to hormonal changes that typically resolves spontaneously, but requires clinical evaluation to exclude mastitis, abscess, or less commonly, malignancy—particularly if the pain is focal, persistent, or accompanied by other symptoms. 1, 2

Understanding the Most Likely Cause

Pregnancy-related breast pain is a normal noncyclic phenomenon that occurs due to hormonal fluctuations and breast tissue changes preparing for lactation. 1 The American College of Radiology explicitly states that "some degree of noncyclic breast pain and tenderness associated with pregnancy and breast-feeding is common and is usually of short duration, resolving spontaneously." 1 Rarely, breast pain can even be one of the first symptoms of pregnancy. 1

The unilateral nature and burning quality warrant attention to rule out other causes, as noncyclical breast pain is typically unilateral, more focal, and predominantly inflammatory rather than hormonal in origin. 1, 2

Critical Differential Diagnoses to Exclude

Infectious/Inflammatory Causes

• Mastitis or breast abscess can present as focal burning pain that may precede the classic signs of induration, redness, warmth, and fever. 1, 2 This is particularly important in pregnancy as it can progress rapidly.
• Mondor disease (thrombophlebitis of the thoracoepigastric vein) may initially present as breast pain and can occur during pregnancy. 1, 2

Extramammary (Non-Breast) Causes

10-15% of "breast pain" actually originates outside the breast, as the breast's nerve supply from intercostal nerves T3-T5 means irritation anywhere along their course can cause perceived breast pain. 1, 2 Key considerations include:

• Costochondritis (Tietze syndrome) is a common chest wall condition that mimics breast pain 1, 2
• Musculoskeletal conditions including pectoral muscle strains or spasms 1
• Cervical or thoracic nerve root syndromes 1

Malignancy Considerations

While uncommon, advanced cancers may present with breast pain as the only symptom, especially if deep in a large breast or with chest-wall invasion. 1, 2 Invasive lobular carcinoma and anaplastic carcinoma are disproportionately associated with mastalgia compared to other cancer types. 1, 2

Clinical Evaluation Algorithm

Physical Examination Must Assess:

• Precise localization: Can the patient point to one specific focal area versus diffuse pain? 1
• Skin changes: Look for erythema, warmth, induration suggesting infection 1, 2
• Palpable masses or cords: A cord-like structure suggests Mondor disease 1
• Reproducibility with chest wall palpation: Suggests musculoskeletal origin 1
• Fever or systemic symptoms: Indicates possible infection requiring urgent treatment 1, 2

Imaging Recommendations

The approach depends on age and clinical findings:

• For pregnant women <30 years with focal pain: Ultrasound alone is first-line to avoid radiation exposure 2, 3, 4
• For pregnant women ≥30 years with focal pain: Diagnostic mammography with ultrasound (though mammography may be deferred in pregnancy if ultrasound is reassuring) 2, 4
• If infection is suspected: Ultrasound is first-line regardless of age 2
• Diffuse, non-focal pregnancy-related pain without concerning features: No imaging required 3, 4

Critical caveat: The American College of Radiology warns that focal, unilateral breast pain without additional signs of breast disease may still need evaluation to exclude underlying lesions. 1, 2 Never dismiss focal breast pain without proper evaluation, as some cancers can present with pain alone. 2, 5

Treatment Approach

First-Line Conservative Management

Most pregnancy-related breast pain resolves spontaneously and responds to reassurance plus supportive measures: 1, 6

• Reassurance after appropriate evaluation—this alone resolves symptoms in 86% of mild cases and 52% of severe cases 5, 6
• Well-fitted supportive bra (properly fitted, worn day and night if needed) 5, 3
• Acetaminophen for symptomatic relief (preferred in pregnancy) 4
• Ice packs or heating pads applied to the affected area 5, 3
• Avoid caffeine and high-fat foods (though evidence is limited) 6, 3

When Conservative Measures Fail

If pain persists despite conservative management:

• Topical NSAIDs can be considered as second-line (though systemic NSAIDs should be avoided in third trimester) 5, 3
• Physical therapy with stretching exercises if musculoskeletal component is identified 5
• Treat underlying cause if mastitis, abscess, or other specific etiology is identified 1, 2

Medications to Avoid in Pregnancy

Do not use danazol, tamoxifen, or bromocriptine—these are effective for severe mastalgia but have potentially serious adverse effects and are contraindicated in pregnancy. 7, 3

Common Pitfalls to Avoid

• Never dismiss unilateral focal breast pain without clinical evaluation, even in pregnancy, as malignancy can present with pain alone 2, 5
• Always rule out extramammary causes (costochondritis, cervical radiculopathy) when breast exam and imaging are normal 2, 8
• Do not routinely image diffuse, bilateral, or clearly hormonal breast pain in pregnancy—this leads to unnecessary healthcare utilization without improving outcomes 1, 3
• Do not delay evaluation of suspected mastitis—this requires prompt antibiotic therapy to prevent abscess formation 1, 2