What could be causing breast pain and spontaneous milk expression in a female of childbearing age with a history of breastfeeding and a current progestin-only birth control implant (e.g. Nexplanon), one year after stopping breastfeeding?

Breast Pain and Milk Expression One Year Post-Breastfeeding with Progestin Implant

This presentation most likely represents persistent galactorrhea with noncyclical mastalgia, requiring diagnostic mammography with ultrasound to exclude underlying pathology, followed by evaluation for hyperprolactinemia if imaging is normal. 1

Understanding the Clinical Picture

The combination of breast pain and continued milk expression one year after stopping breastfeeding is concerning and warrants thorough evaluation. This is noncyclical mastalgia (unilateral or focal breast pain without menstrual cycle relationship) which accounts for approximately 25% of breast pain cases and requires additional workup to exclude underlying breast lesions. 2

Key Characteristics of Noncyclical Mastalgia:

• Predominantly inflammatory rather than hormonal in nature 2
• Usually unilateral and focal, often in the subareolar area or nipple 2, 1
• Does not respond to hormonal manipulation 2
• Spontaneously resolves in up to 50% of patients, but requires evaluation first 2

Immediate Diagnostic Approach

First priority: Rule out breast pathology with diagnostic mammography and ultrasound. 1 This is essential because:

• Noncyclical mastalgia may indicate an underlying benign or malignant breast lesion 2
• Mammography may reveal duct ectasia or secretory calcifications at the site of pain 2, 1
• While breast cancer rarely presents with pain alone (0-3% risk), proper evaluation is mandatory 1

Specific Findings to Look For:

• Duct ectasia (common benign cause of subareolar pain in women in their 40s) 1
• Secretory calcifications 2
• Focal masses or architectural distortion 2
• Signs of periductal mastitis 1

Addressing the Galactorrhea

If imaging is normal, evaluate for hyperprolactinemia as the cause of persistent milk expression. This is critical because:

• Galactorrhea one year post-weaning is abnormal and suggests ongoing prolactin stimulation 2
• Progestin-only contraceptives (like the implant) do not typically cause galactorrhea, as they don't affect milk volume or composition 3
• Persistent lactation requires serum prolactin level measurement and potentially thyroid function tests

Common Pitfall to Avoid:

Do not attribute the galactorrhea to the progestin implant without proper workup. Progestin-only contraceptives are specifically chosen during lactation because they don't affect milk production, so they shouldn't be causing milk expression a year after weaning. 3

Symptomatic Management While Awaiting Workup

Prescribe NSAIDs (ibuprofen or naproxen) for pain relief. 4, 5 These are:

• Safe and effective for breast pain 4
• First-line pharmacological treatment for noncyclical mastalgia 5

Additional Supportive Measures:

• Well-fitted supportive bra, especially during physical activity 4, 5
• Ice packs or heating pads for comfort 5, 1
• Reassurance that most noncyclical pain resolves spontaneously 2

When to Escalate Care

Return for reassessment if: 1

• Pain characteristics change or worsen
• New symptoms develop (fever, erythema, warmth, palpable mass)
• Systemic symptoms suggesting infection appear
• No improvement after 48-72 hours of conservative management 4

Critical Differential Diagnoses to Consider

Beyond simple galactorrhea and mastalgia, evaluate for:

• Duct ectasia or periductal mastitis (most common benign causes in this age group) 1
• Prolactinoma or other causes of hyperprolactinemia (medications, hypothyroidism)
• Mastitis or breast abscess (though less likely without fever or erythema) 2
• Mondor disease (thrombophlebitis of breast veins) 2

The Role of the Progestin Implant

The birth control implant is unlikely to be the primary cause because:

• Progestin-only contraceptives don't affect milk volume or composition 3
• They're specifically recommended during lactation for this reason 3
• However, if all other causes are excluded and symptoms persist, consider discussing alternative contraception with the patient

Bottom line: This requires diagnostic imaging first, then targeted treatment based on findings. Do not dismiss as simple hormonal fluctuation without proper workup. 1