FNA Biopsy / Fine-Needle Aspiration Biopsy

Fine-needle aspiration
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Fine-needle aspiration (FNA) is a diagnostic procedure used to investigate lumps or masses. In this technique, a thin (23-25 gauge), hollow needle is inserted into the mass for a sampling of cells that, after being stained, will be examined under a microscope (biopsy). The sampling and biopsy considered together are called fine-needle aspiration biopsy (FNAB) or fine-needle aspiration cytology (FNAC) (the latter to emphasize that any aspiration biopsy involves cytopathology, no histopathology).

Medication Uses of FNA

This type of sampling is performed for one of two reasons:

  • A biopsy is performed on a lump or a tissue mass when its nature is in question.
  • For known tumors, this biopsy is performed to assess the effect of treatment or to obtain tissue for special studies.

When the lump can be felt, the biopsy is usually performed by a cytopathologist or a surgeon. In this case, the procedure is usually short and simple. Otherwise, it may be performed by an interventional radiologist, a doctor with training in performing such biopsies under x-ray or ultrasound guidance. In this case, the procedure may require more extensive preparation and take more time to perform.

Also, fine-needle aspiration is the main method used for chorionic villus sampling, as well as for many types of body fluid sampling.

It is also used for ultrasound-guided aspiration of breast abscess, breast cysts, and seromas.

List of body fluids that aspiration

  • Amniotic fluid
  • Aqueous humor and vitreous humor
  • Bile
  • Blood
  • Blood plasma
  • Blood serum
  • Breast milk
  • Cerebrospinal fluid
  • Cerumen (earwax)
  • Chyle
  • Chyme
  • Endolymph and perilymph
  • Exudates
  • Feces – see diarrhea
  • Female ejaculate
  • Gastric acid
  • Gastric juice
  • Lymph
  • Mucus (including nasal drainage and phlegm)
  • Pericardial fluid
  • Peritoneal fluid
  • Pleural fluid
  • Pus
  • Rheum
  • Saliva
  • Sebum (skin oil)
  • Serous fluid
  • Semen
  • Smegma
  • Sputum
  • Synovial fluid
  • Sweat
  • Tears
  • Urine
  • Vaginal secretion
  • Vomit

By type

  • Intracellular fluid
  • Extracellular fluid
  • Intravascular fluid (blood plasma)
  • Interstitial fluid
  • Lymphatic fluid (sometimes included in interstitial fluid)
  • Transcellular fluid

Indications of FNA

  • Infection


  • Needle aspiration is one method by which you can obtain material for bacteriological examination. This procedure should be considered in ,
  • Children with pneumonia
  • Adults unable to produce sputum
  • An immunocompromised patient with opportunistic infections


Mass lesions in the thorax are the prime indication for needle aspiration biopsy. All intrathoracic nonvascular masses irrespective of their location can be biopsied. This includes lung mediastinal, pleural, and chest wall masses. This form of biopsy is best suited for confirmation of malignancy

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Diffuse infiltrative lung process

Diffuse lung disease is one of the indications for needle aspiration. The procedure is likely to be of benefit in establishing a malignant or infectious etiology. It is not useful in confirming others etiologies for diffuse lung disease. Fine needle aspiration provides material for the cytological and bacteriological exam only.  In general, it does not provide tissue for histological exams. Modifications of needles have made it possible to have a small core of tissue. Benign tumors and granulomas can be diagnosed only by histological exam of tissue. The larger the core of tissue the needle can provide, the higher the complication. These issues enter in the selection of needles and indications for the procedure.

Contra-Indications of FNA

For superficial FNA, most contraindications are relative rather than absolute.FNA may be preferable in at-risk patients with significant comorbidities who cannot tolerate a more invasive procedure (surgery) for diagnosis possible contraindications for superficial FNA biopsy include
  • Uncooperative or excessively apprehensive patient
  • For thyroid, those who cannot suppress their cough reflex: at risk for thyroid laceration by needle

Certain tumors and tumor-like conditions

  • Paragangliomas (including carotid body tumors): possible risk of syncope, acute hypertension, hemorrhage
  • Echinococcal cyst and suspected hydatid disease: rare risk of anaphylaxis including fatal reactions and cyst rupture
  • Highly vascular lesions (i.e. vascular malformation): at risk for hemorrhage and non-diagnostic FNA

Controversial and not currently supported

  • FNA of testicular malignancies: theoretical, but not proven, risk of tumor implantation
  • Factors that put the patient at risk for complications during or after the superficial FNA biopsy:
    • Bleeding disorders or anticoagulant therapy (e.g. aspirin, Coumadin, Plavix): especially for head and neck FNA (e.g. thyroid), where possible bleeding/hematoma formation has the potential for mass effect leading to airway compromise
  • Superficial FNA is a BIOPSY and has possible complications, albeit rare, that are almost always minor
  • The overwhelming volume of literature supports the safety of FNA
  • Superficial FNA (i.e. targets that are above the fascia) have a lower complication rate than FNA of deep-seated organs (e.g. liver, lung, kidney)
  • Complications arise exponentially with increasing needle size and FINE needles (22 gauge needle or smaller diameter needle) have the lowest complication rates
  • Generally, the more experienced the aspirator, the fewer the complications
  • The most commonly encountered complications for superficial FNA include:
    • Minor pain/discomfort (increases with needle size)
    • Bleeding (ecchymosis/hematoma)
  • Small hematomas (0.3 – 26%)Pain / discomfort (up to 92%) (minor, transient and well tolerated)
  • Massive hematomas (rare, 5 – 10 reported cases)
  • Hemorrhage/hematoma:
  • Neuritis following hematoma (extremely rare, < 5 reported cases)
  • Pseudoaneurysm (extremely rare, < 5 reported cases)
  • Carotid hematoma (extremely rare, < 5 reported cases)
  • Secondary hemangioma (extremely rare, < 5 reported cases)
  • Acute transient swelling (extremely rare, < 5 reported cases)
  • Delayed transient swelling (extremely rare, < 5 reported cases)
  • Infection (rare, 5 – 10 reported cases)
  • Recurrent laryngeal nerve palsy (0.036 – 0.9%)
  • Vasovagal reaction (0.5 – 1.3%)
  • Tracheal puncture (0.3%)
  • Dysphagia (extremely rare, < 5 reported cases)
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Needle track seeding

  • Papillary thyroid carcinoma (0.14%)
  • Other thyroid carcinomas (extremely rare, < 5 reported cases)
  • Nodule volume alterations (13 – 35%) (e.g. nodule volume change > 50% over baseline)
  • Post aspiration thyrotoxicosis (1%)


  • Rare known complication resulting from superficial FNA of a target on or near the chest, including breast, supraclavicular area, and axilla, especially in thin patients
  • May be a more common complication in the hands of trainees.Estimated at 0.01 – 0.18% (although as high as 1 in 417 has been reported)

Techniques that may help decrease this complication include:

  • Maintain the aspirating needle parallel or tangential to the chest wall
  • Pulling a mobile lump away from the chest wall for the FNA
  • Performing the aspiration in the area of the lump which overlays a rib to further decrease the chance of pleural penetration

Post FNA infarction of the target and additional biopsy tissue alterations

  • Can occur with any biopsy method
  • The smaller the needle, the less likely the tissue alterations will occur
  • Rare event with most reported cases occurring after FNA biopsy of a neoplasm
  • Partial or total infarction may cause varying degrees of difficulty in a histologic examination of surgical specimen and confirmation of cytologic diagnosis
  • Infarctions/necrosis may be more common in Hürthle cell tumors but both benign and malignant tumors may undergo these changes
  • The surgical pathologist should be told that prior fine needle biopsy was performed and given the cytologic diagnosis

Additional FNA biopsy tissue alterations that may be seen

  • Hemorrhage / hemosiderin-laden macrophages
  • Granulation tissue and benign spindle cell and endothelial proliferation
  • Fibrosis
  • Displaced nonneoplastic epithelium
  • May simulate malignancy
  • Seen within FNA needle tract or perineural location
  • Fat necrosis

Needle track seeding by tumor

  • Attracts much attention in medical literature and a maybe major concern to some patients
  • Should not be a deterrent to FNA when indications are appropriate
  • Is extremely rare to use FINE needles as defined above when compared with large bore needle biopsies (e.g. larger diameter needle than 22 gauge) or open/incisional surgical biopsies
  • Estimated frequency of 0.003 – 0.009% for all FNA sites using FINE needles
  • Most case reports of needle tract seeding occur with malignant tumors that are aggressive or present at the high stage at diagnosis
  • Conflicting reports on whether needle tract seeding by malignant tumors is an unfavorable prognostic sign
  • Early detection is probably important – effective treatment includes surgical removal, ablation, radiation

Very rare needle tract seeding by benign tumors, tumors like conditions and even normal tissue has been reported

  • Parathyroid tissue
  • Parathyroid adenoma
  • Endometriosis
  • Pleomorphic adenoma
  • Colorectal adenoma
  • Breast papilloma
  • Metanephric adenoma of the kidney
  • Thymoma
  • Hemangioma


  • Fatalities have been reported with all types of biopsy methods and FNA biopsy has the best safety record
  • Single case reports of death from aspiration following a carotid body tumor and a fatal case of cervical edema following FNA have occurred
  • The mortality rate for FNA of deep-seated organs (e.g. liver, kidney, lung) has been reported up to 0.031%

What are the risks of a breast FNA?

The risks of a breast FNA are rare and minimal and can include:

  • Minimal bleeding and bruising, especially for those on anticoagulation (warfarin, heparin), aspirin, or anti-platelet medication.
  • The risk of infection is rare. Breast FNA is a clean and sterile procedure, which uses skin antiseptic and disposable one-use needles.
  • Breast implant perforation can happen if the lesion is close to the implant but is a rare complication using ultrasound or stereotactic (mammography) guidance.
  • Pneumothorax (perforation of the lung cover by the needle with lung collapse) is an extremely rare but serious complication that is more frequent if the lesion is deeply located in a small breast.
  • If the lesion being biopsied is found to be cancer, there is a very small risk of displacement (“seeding” or implantation) of tumor cells along the track or path of the needle as it is withdrawn from the breast. This is extremely rare.
  • Breast FNA may not always provide a definitive diagnosis (or answer) about what the lesion in your breast is. In particular, it may not allow cancer to be definitely ruled out even if no cancer cells are found in the samples of material removed from your breast. The result of the FNA needs to be considered along with the results of other breast imaging and your doctor’s examination findings.
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Final Cytology Report 

The final cytology report should contain the following information:

  • 1) a comment on the adequacy of the specimen obtained
  • 2) a comment on the general diagnostic category (negative for malignancy, positive for malignancy, or suspicious or inconclusive for malignancy)
  • 3) specific diagnosis, differential diagnosis, or descriptive diagnosis. Cytologic findings should not be interpreted within a vacuum; it is important to correlate cytologic findings with clinical and radiologic findings. Further work-up, including possible tissue biopsy, is indicated if there is a lack of correlation between the cytologic findings and clinical suspicion.


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