Fine-needle aspiration of a lump

What it is

Fine-needle aspiration (FNA) samples cells from a mass through a thin needle, usually 22–27 G, for cytology. It is quick, cheap, done in clinic with little or no anaesthetic, and has few complications, which makes it a first-line test for palpable lumps of the thyroid, lymph nodes, breast, salivary glands and soft tissues; lesions that cannot be felt, and most thyroid nodules, are sampled under ultrasound. The needle is moved back and forth through the lesion in several quick passes, with or without suction from a syringe; capillary action alone fills the needle and often gives a less bloody sample. The material is expressed onto glass slides and smeared, some slides air-dried and others fixed at once in alcohol, and the needle can be rinsed into a liquid medium for a cell block, flow cytometry or microbiology. FNA gives cells, not tissue architecture: it can show cancer, infection, a cyst or a reactive node, but it cannot always separate a follicular adenoma from carcinoma or classify a lymphoma, and a non-diagnostic or benign result that does not match the clinical picture is repeated or followed by core or excision biopsy. Thyroid results are reported with the six-category Bethesda system.

Indications

• Palpable neck lump: thyroid nodule, enlarged lymph node, salivary gland mass or branchial cyst.
• Thyroid nodules with suspicious ultrasound features or above the size thresholds of the reporting system.
• Breast lump as part of triple assessment; aspiration of a simple cyst also treats it.
• Soft-tissue and subcutaneous lumps, and suspected metastatic nodes in a patient with known cancer.
• Fluid collections or suspected infection, to obtain material for culture, including mycobacteria.

Contraindications and precautions

• Pulsatile mass or suspected vascular lesion (aneurysm, carotid body tumour): image first.
• Suspected hydatid cyst: puncture risks spillage and anaphylaxis.
• Severe coagulopathy or anticoagulation: usually manageable with a fine needle and pressure, but correct major defects first.
• Infection of the overlying skin; an uncooperative patient who cannot keep still.
• Deep lumps near the pleura (supraclavicular, axillary, chest wall): angle the needle tangentially or use ultrasound to avoid pneumothorax.

Equipment

• Gloves, alcohol or chlorhexidine swabs and gauze.
• Fine needles (22–27 G) and a syringe, with or without a syringe holder (aspiration gun) for suction with one hand.
• Labelled glass slides, a spreader slide, a jar of alcohol fixative and a holder for air-dried slides.
• A tube of liquid medium or saline for cell block, flow cytometry or culture.
• Ultrasound with a linear probe for non-palpable or deep lesions and for thyroid nodules; a small dressing.

Step by step (and why)

1. Review imaging, explain the test and its possible non-diagnostic result, and consent — a repeat is common and should not surprise the patient.
2. Position to make the lump prominent (neck extended for thyroid) and fix it between two fingers — a stable target gives more cells.
3. Clean the skin; anaesthetic is usually unnecessary for thin needles — the injection hurts as much as the pass.
4. Insert the needle into the lump and move it briskly back and forth in a fan, with or without suction — cutting edges free the cells.
5. Stop when material appears in the hub and release suction before withdrawing — this keeps the sample in the needle, not the syringe.
6. Expel drops onto slides and smear gently; fix some at once in alcohol and air-dry others — each stain needs its own preparation.
7. Rinse the needle in liquid medium and do 2–4 passes as needed — the rinse allows a cell block and extra tests.
8. Press on the site for a few minutes and apply a dressing — pressure prevents haematoma, the most common complication.
9. Label every slide and request with the site, history and question — the cytologist interprets cells in their clinical context.

Preparing the FNA sample: what each preparation is for.

Complications

• Pain and bruising or haematoma at the site, the most common problems.
• Vasovagal reaction during the procedure.
• Infection of the site, uncommon with clean technique.
• Pneumothorax after sampling lumps near the pleura (breast, axilla, supraclavicular fossa).
• Non-diagnostic sample needing a repeat; needle-tract seeding of tumour is very rare.

Next step

• Non-diagnostic or inadequate sample: repeat the FNA, under ultrasound if it was done by palpation.
• Malignant or suspicious cytology: refer to the relevant surgical or oncology team with the report and imaging.
• Cytology suggesting lymphoma, or a benign result that does not match the clinical concern: arrange core or excision biopsy.
• Thyroid: manage by the Bethesda category, from ultrasound follow-up for benign nodules to surgery for malignant ones.
• Tell the patient when and how the result will be given, and to return with a growing swelling, fever or breathlessness.

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Elsewhere in DurgiPedia

• Thyroid examination
• Lymph node examination
• Clinical breast examination
• Approach to a neck lump in adults
• Thyroid nodule and follicular adenoma
• Informed consent: elements and how to obtain it

Connections

← All clinical skills

Educational content; it does not replace supervised hands-on training, your institution's protocols or a prescriber's order. A procedure is learnt with a teacher and done only once you are trained to do it.

Sources: Fine Needle Aspiration (StatPearls (NCBI Bookshelf), 2022).

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Representative model, for educational purposes only.