Fine Needle Aspiration (FNA)

Biopsy of subepithelial mass

A neck mass of uncertain origin may be evaluated by fine-needle aspiration biopsy (FNA). This procedure is easy to perform and provides a quick, reliable diagnosis when positive, but not when negative, without complicating later attempts at curative surgery. The exception to this is a mass within the parotid gland. Although reliability of parotid FNA is good, the needle tracts release digestive enzymes into the gland, making subsequent histologic evaluation unreliable to the point that some experts refuse to consult on such specimens.

Open biopsy of neck masses should not be performed unless FNA, paranasal sinus x-rays, and panendoscopy with random biopsy of Waldeyer’s ring under general anesthesia have failed to reveal a diagnosis. An open biopsy incision in the neck is placed so as to not interfere with future management, and is best performed by the surgeon who has the ultimate responsibility for the patient’s care.

 

FNA technique:

If the needle is to be inserted through skin, prep the area with alcohol.  Avoid injection of local anesthesia because it interferes with palpation of the local tissue, and it is not needed.  On mucosal surface topical anesthesia is used. 

Fit a 10 cc leuer lock syringe with a 22 gage, 1 ½ inch needle and place  this unit into the Cameco suction device (Cameco Ltd, London, # 391 920-E) which is then held in the dominant hand. Fix the mass with the non dominant hand. Insert the needle lateral to, not directly over the mass. This allows approaching the mass from the side and provides a better feel of where the needle tip is related to the mass.

The cortex of the mass is its most critical part. So, apply suction when the mass is reached. Even solid masses can become necrotic in their center and the cortex may be the only source of evaluable tissue. So maintain suction and make several passes into and out of the mass at the level of the cortex. Then sample the remainder of the mass via multiple passes under suction. If fluid is encountered, do not aspirate until the cortex has been well sampled.

Obtain at least two samples (the needle is withdrawn and reinserted for each); if lymphoproliferative disorder is suspected, obtain a third sample; fluid aspirate is a fourth sample.

 

Processing:

Contents of the first sample are placed onto a glass slide, smeared with a second slide, and both slides are placed into alcohol. Contents of the second sample are flushed into a tube with cytology collection fluid (Surepath vials). Because the main diagnostic fragments frequently are located within the needle, flush the needle thoroughly using cytology collection fluid. If  lymphoproliferative disorder is suspected, the third sample is flushed into flowcytometry solution (RPMI). Fluid aspirate is flushed into standard cytology collection fluid (Surepath vials).

Notify the staff to transport the specimens immediately to  the appropriate laboratories: Cytopathology for Surepath samples; the Hematology Clinical Laboratory for Flowcytometry samples.

 

For FNA video, open: Fine Needle Aspiration

 

The Cytopathology Lab prepares the specimens using the Surepath system and the Pappanicolaou staining methodology. 

The residual fluid present in the vial is centrifuged and the residual pellet is submitted to the histology laboratory. After paraffin embbeding and sectioning, slides are stained with hematoxylin and eosin (cell block slides). Diagnostic material present in the paraffin “cell block” can be used for such ancillary studies as immunohistochemistry, molecular studies or electron microscopy.

 

Pieter Noordzij MD

Charles W Vaughan MD

Primary teaching affiliate
of BU School of Medicine