Fine-needle aspiration biopsy (FNAB)

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For FNA biopsy, most use "fine" or "thin" needles ranging from 22 to 27 gauge (commonly, 25 gauge). As the name indicates, the biopsy technique uses aspiration to obtain cells or fluid from a mass.

Local anaesthesia is not routinely used for FNAB. If needed, a small amount (0.5 to 1.0 ml) of 1% lidocaine without epinephrine can be infiltrated locally to produce a skin wheal only, in order not to obscure the nodule.

Equipment (Fig. 1)

• Alcohol prep pads
• 10 or 20 ml syringe (with or without the syringe holder – Fig. 2)
• ½-inch 25 gauge needle
• Glass microscope slides (2)
• Spray fixative, gauze

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Fig. 1. Fine-needle aspiration biopsy set (spray fixative not included)

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Fig. 2. FNAB: the syringe with (A) and without the holder (B)

The syringe holder (e.g. the Cameco Syringe pistol as shown in this Fig.) serves as a handle which holds the syringe and also guides the needle, giving the operator a free hand to work with.

Patient’s positioning

• Breast lesions: upper quadrant – an upright seated position; lower quadrant – a supine position (Fig. 3A)
• Thyroid nodules: a supine position with a roll placed behind the patient’s shoulders
• Lymph nodes and soft tissue lesions: depends on location of lesions

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Fig. 3. Palpable breast lump (A), immobilized and punctured (B)

Technique details (Chen H, Sonnenday CJ, Lillemoe KD (eds), 2000) , (Cracknell ID, Mead MG, 1997)

• The skin over the lump is cleansed with an alcohol swab
• The lesion is immobilized between two fingers of one (non-dominant) hand (Fig. 3B)
• A 22-gauge needle attached to a well-fitted syringe is advanced into the lesion (Fig. 3B)
• Once the lesion is entered, a full 10 ml of suction is applied to the syringe and maintained
• The needle is gently moved back and forth through the lesion several (e.g. 3-6) times in different directions to obtain a representative sample of tissue (Fig. 4)

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Fig. 4. Fine-needle aspiration biopsy of the breast lump
• Before withdrawing the needle from the lesion, pressure on the plunger is released to eliminate the vacuum
• The puncture site is compressed and finally covered with an adhesive dressing

How to proceed with the tissue sample

The specimen should be within the needle and hub, but not in the syringe, otherwise it may be lost After detaching the needle from the syringe, the latter should be filled with air, the needle reattached, and the obtained material expelled onto a glass microscope slide (with the bevel at a 45-90^o angle to the slide surface) (Fig. 5)
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Fig. 5. FNAB: expelling the obtained material (A) onto a glass slide (B)
• A thin smear is prepared by using the second glass slide to gently press down and draw out the material to a feathered edge (Fig. 6)
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Fig. 6. FNAB: making a smear – pressing down (A) and drawing out the material (B)
• The smear should be air dried or fixed immediately in 95% alcohol or with commercially available cytological spray fixative (Fig. 7)

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Fig.7. FNAB: the smear is ready (dried or fixed)
• Before dispatching the sample to the laboratory (Fig. 8), it should be labelled with the patient’s name, DOB, etc. (details of the site and lesion characteristics should also be provided, together with a brief history of the patient’s complaints and symptoms) (Cracknell ID, Mead MG, 1997) , (Goldberg A, Stansby G (eds), 2005)
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Fig. 8. FNAB: the smears ready for labelling (A) and dispatching (B)
• Laboratory work-out: The slide is stained with either Papanicolaou stain or H&E (haematoxylin and eosin) and assigned a cytology code, e.g. C1 - insufficient material to make a diagnosis; C2 – benign cells seen; C3 – uncertain about the diagnosis; C4 – probably cancer; C5 – cancer (Goldberg A, Stansby G (eds), 2005)

Glossary

thyroid

The thyroid (from the Greek word for \"shield\", after its shape) is one of the larger endocrine glands in the body. It is a double-lobed structure located in the neck and produces hormones, principally thyroxine (T4) and triiodothyronine (T3), that regulate the rate of metabolism and affect the growth and rate of function of many other systems in the body.