What to do if a breast lump develops while using Nexplanon (etonogestrel)?

Evaluation and Management of Breast Lump While Using Nexplanon

If a breast lump develops while using Nexplanon, proceed immediately with age-appropriate imaging evaluation—diagnostic mammography for women ≥40 years or targeted breast ultrasound for women <30 years—and do not remove the Nexplanon until imaging and potential biopsy determine whether the lump is benign or malignant. 1

Initial Imaging Based on Age

For women ≥40 years:

• Begin with diagnostic mammography including standard mediolateral oblique and craniocaudal views of both breasts, with a radio-opaque marker placed directly over the palpable finding 1
• Mammography detects 86-91% of breast cancers in this age group 2
• Always follow mammography with targeted breast ultrasound regardless of mammography results, as ultrasound detects 93-100% of cancers that are occult on mammography 2, 1

For women <30 years:

• Proceed directly to targeted breast ultrasound as the initial study, avoiding unnecessary radiation exposure in this low-risk population where breast cancer incidence is <1% 2, 1
• Mammography is not indicated unless ultrasound shows suspicious findings or clinical examination is highly suspicious 1

For women 30-39 years:

• Either ultrasound or diagnostic mammography is appropriate as the initial approach, depending on clinical suspicion 1

Critical Timing and Sequencing

Never perform biopsy before imaging, as biopsy-related changes will confuse, alter, obscure, and limit subsequent image interpretation 2, 1

The combined negative predictive value of mammography and ultrasound is >97% when both are benign 2, 1, making this dual-modality approach highly reassuring when results are concordant.

Management Based on Imaging Results

If imaging shows suspicious findings (BI-RADS 4-5):

• Proceed directly to image-guided core biopsy (ultrasound-guided or mammography-guided) rather than fine-needle aspiration 1
• Core biopsy is superior in sensitivity, specificity, and correct histological grading 1
• Continue Nexplanon during the diagnostic workup—there is no indication to remove it before establishing a diagnosis

If imaging shows clearly benign features:

• Return to clinical follow-up only, with no further imaging or biopsy needed 1
• Continue Nexplanon without interruption
• Benign findings include simple cysts, benign lymph nodes, lipomas, or hamartomas 1

If a suspicious physical examination persists despite negative imaging:

• Biopsy should be performed guided by palpation, regardless of negative imaging findings 2

Nexplanon Continuation Decision

Nexplanon does not need to be removed during breast lump evaluation unless:

• Malignancy is confirmed on biopsy, at which point contraceptive management should be discussed with the oncology team
• The patient desires removal for other reasons

Nexplanon (etonogestrel implant) is a progestin-only contraceptive that provides >99% contraceptive efficacy for 3 years 3, 4. There is no contraindication to continuing Nexplanon during breast lump evaluation, as the diagnostic workup takes priority over contraceptive method changes.

Special Populations

For pregnant or lactating women:

• Ultrasound is often the first modality chosen due to tissue density that limits mammographic evaluation 2, 1
• However, mammography is not contraindicated during pregnancy or lactation and should be performed if malignancy is suspected, as it has 90-100% sensitivity for detecting malignancy in this population 2, 1

Common Pitfalls to Avoid

• Do not delay imaging evaluation—physical examination alone is unreliable, with even experienced examiners showing only 73% agreement on the need for biopsy among proven malignancies 1
• Do not order MRI, PET, or molecular breast imaging as initial evaluation, as these have no role in the workup of a palpable mass 2, 1
• Do not rely on diagnostic mammography alone—ultrasound must also be performed 1
• Do not remove Nexplanon preemptively before completing the diagnostic evaluation