A Benign FNA in a BIRADS 4C Breast
A 46-year-old woman presents to a surgical outpatient clinic with a painless 2.8 cm mass in the upper outer quadrant of the left breast, first noticed three weeks ago. The skin over it is tethered, and there is a 1.5 cm mobile node in the left axilla. Mammography and ultrasound describe a spiculated, hypoechoic mass with posterior acoustic shadowing, scored BIRADS 4C, with no suspicious microcalcifications and no other lesions in either breast. A general practitioner performed a freehand FNA two weeks earlier; the report reads 'benign ductal epithelial cells, no atypia, scant cellularity'. She is a widow with three dependent children, works as a schoolteacher, and wants 'the lump removed this week so I can get on with my life'. She has no other comorbidity and takes no regular medication. The hospital has ultrasound, a 14-gauge core biopsy gun and a histopathology service, but no on-site radiation oncology.
1. The FNA report reads 'benign ductal epithelial cells, no atypia'. Explain why you cannot accept this as reassurance, and state your next investigation with technical detail.
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Triple assessment is only reliable when all three limbs agree. A benign FNA in a woman with a hard, tethered 2.8 cm mass and a spiculated BIRADS 4C lesion is a discordant result, and discordance is treated as suspicious regardless of the cytology. FNA has a false-negative rate in the region of 5–20%, and sampling error is common in scirrhous tumours where the needle yields mostly fibrous stroma - note that this report itself says 'scant cellularity'.
Next step: ultrasound-guided 14-gauge core needle biopsy, at least three to four cores taken through the lesion by someone who does breast biopsies routinely, sent in formalin for histology with ER, PR and HER2 requested on the cores.
Why not repeat the FNA: cytology cannot distinguish invasive from in-situ disease, cannot grade reliably, and cannot give receptor status - all of which determine the operation she needs.
Why not go straight to excision: a therapeutic operation should not be the diagnostic step. It commits her to a larger operation with no plan, and if cancer is confirmed she may be better served by neoadjuvant treatment.
If the core is also non-diagnostic, proceed to vacuum-assisted or wire-localised open excision biopsy. Tell her explicitly that the FNA does not exclude cancer.
2. The core biopsy shows grade 2 invasive ductal carcinoma, ER 90%, PR 70%, HER2 IHC 1+, Ki-67 25%, clinically node-negative. What determines whether she receives neoadjuvant chemotherapy or upfront surgery, and what axillary step is required before either?
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With a cT2N0, strongly ER/PR-positive, HER2-negative (IHC 1+ counts as negative; IHC 2+ would need ISH) grade 2 tumour, upfront surgery - wide local excision with clear margins plus sentinel node biopsy - is the standard, provided the tumour-to-breast ratio permits acceptable cosmesis.
Neoadjuvant chemotherapy would be chosen for:
- locally advanced disease (T3/T4, N2/N3, skin or chest wall involvement, inflammatory carcinoma);
- cytologically proven axillary nodal disease, particularly when downstaging the axilla is the goal;
- a tumour too large relative to the breast for conservation, where shrinkage would allow it;
- aggressive biology - HER2-positive or triple-negative - where response rates are high and residual disease guides adjuvant treatment.
Her low-grade, hormone-receptor-rich, HER2-negative tumour is exactly the phenotype that responds poorly to chemotherapy, which argues against the neoadjuvant route on biological grounds.
Before either route: axillary ultrasound with FNA of any suspicious node. A positive FNA converts a clinically node-negative axilla into pathologically node-positive and changes the plan. Staging imaging (CT, bone scan) is indicated only for symptoms or abnormal liver function, not routinely in early disease. Do not perform sentinel node biopsy before neoadjuvant chemotherapy if you intend to use it for decision-making.
3. She declines all treatment and returns eight months later with three weeks of progressive thoracic back pain and new leg weakness. What are your priorities, and what would you deliberately not do?
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This is stage IV disease until proven otherwise, and the emergency is metastatic spinal cord compression, not the pain.
Priorities, in order:
- Protect the cord - whole-spine MRI within 24 hours; if MRI is unavailable, CT myelography. Start dexamethasone immediately (16 mg daily, or 10 mg IV then 4 mg six-hourly) because she already has leg weakness; do not wait for imaging to give the first dose.
- Stabilise - flat bed rest until spinal stability is assessed, urgent spinal surgical/oncological opinion, neurosurgical referral if there is cord compromise.
- Confirm the tissue - she was never treated, so a core biopsy of the breast mass or a bone lesion is needed to confirm ER/PR/HER2 before systemic therapy.
- Systemic plan - endocrine therapy with a CDK4/6 inhibitor if ER-positive and there is no visceral crisis; a bone-modifying agent such as zoledronic acid with calcium and vitamin D; radiotherapy to the involved vertebrae; analgesia.
What I would not do: I would not send her home with analgesics and a routine follow-up, and I would not perform a lumbar puncture in a patient with suspected cord compression. Delay here costs her the ability to walk.