What are the next steps for a female patient with a growing firm lump in her right breast, which has increased in size over time?

Urgent Imaging and Specialist Referral Required

A growing firm breast lump requires immediate imaging evaluation with targeted ultrasound (within 2 weeks), followed by urgent referral to a breast specialist if findings are suspicious or indeterminate, as any enlarging breast mass cannot be assumed benign regardless of clinical features. 1, 2

Immediate Next Steps

Initial Imaging (Within 2 Weeks)

For patients under 30 years:

• Proceed directly to targeted breast ultrasound as the initial study, avoiding unnecessary radiation in this low-risk population 1, 2
• Do NOT perform mammography first unless ultrasound shows suspicious findings 1

For patients 30 years or older:

• Begin with diagnostic mammography (both breasts, with radio-opaque marker over the palpable lump), followed by targeted ultrasound regardless of mammography results 2
• Ultrasound must be performed even if mammography appears normal, as ultrasound detects 93-100% of cancers occult on mammography 2

Critical Pitfall to Avoid

Never delay imaging based on clinical impression alone - even experienced examiners show only 73% agreement on biopsy decisions for proven malignancies, and physical examination is unreliable for determining benignity 1, 2

Management Based on Imaging Results

If Ultrasound Shows Suspicious Features (BI-RADS 4-5):

• Immediate referral to breast specialist for image-guided core needle biopsy - this is mandatory and should occur within days, not weeks 2, 3
• Core biopsy is superior to fine needle aspiration for sensitivity, specificity, and correct histological grading 2
• The specialist will verify concordance between pathology, imaging, and clinical findings 3

If Ultrasound Shows Indeterminate or Equivocal Features:

• Urgent breast specialist referral is required when the radiologist expresses uncertainty or cannot rule out malignancy 3
• Any statement that "aggressive solid mass should not be ruled out" effectively assigns BI-RADS 4 category and mandates tissue diagnosis 3
• Do NOT observe without biopsy - observation is only appropriate for clearly benign findings 3

If Ultrasound Shows Clearly Benign Features (Simple Cyst, Lipoma):

• Return to clinical follow-up only, no further imaging needed 1, 2
• The combined negative predictive value of mammography and ultrasound is >97% when both are benign 2

If Ultrasound Shows Solid Mass with Benign Features:

• Short-interval ultrasound follow-up at 6 months, then every 6-12 months for 1-2 years 1
• Consider immediate biopsy if patient has high anxiety, high-risk factors, or is planning pregnancy 1

Special Consideration: Soft Tissue Sarcoma

Given the description of a "firm lump" that has grown larger, soft tissue sarcoma must be considered in the differential diagnosis, particularly breast sarcoma or malignant phyllodes tumor 4:

• Any unexplained lump increasing in size warrants urgent ultrasound within 2 weeks 4
• If ultrasound findings are uncertain and clinical concern persists, suspected cancer pathway referral is indicated 4
• Breast sarcomas and malignant phyllodes tumors should be referred to specialist sarcoma centers for pathology review and multidisciplinary team discussion 4

Absolute Contraindications

Do NOT:

• Perform biopsy before completing imaging workup - biopsy changes will confuse subsequent image interpretation 1, 2
• Order MRI, PET, or molecular breast imaging as initial evaluation - these have no role in initial workup of a palpable mass 1, 2
• Assume benignity based on clinical features alone - even "firm" or "well-defined" masses can be malignant 1
• Delay evaluation for menstrual cycle observation if the patient is 30 years or older 4

High-Risk Features Requiring Expedited Workup

Immediate imaging and specialist referral if:

• Strong family history of breast or ovarian cancer 2
• Known BRCA mutation or other hereditary cancer syndrome 2
• Prior breast cancer history 2
• Rapid growth over weeks to months 4
• Size >5 cm 4