Fine-Needle Aspiration of Neck Masses
- Author: Jonas T Johnson, MD, FACS; Chief Editor: Arlen D Meyers, MD, MBA more...
Physicians are often asked to evaluate a patient with a solitary neck mass. Clinical evaluation of a solitary neck mass can be difficult because of the extensive differential diagnoses (listed below). An important factor in determining the differential diagnoses is the age of the patient. Individuals younger than 40 years are overwhelmingly diagnosed with benign processes such as congenital and inflammatory lesions. In patients older than 40 years, the differential diagnoses shift, as more than 60% of lesions are associated with malignancy.
Differential diagnoses of neck masses
See the list below:
- Squamous cell carcinoma (SCC)
- Adenocarcinoma (most commonly from salivary gland origin)
- All other primary sites imaginable have been reported.
Primary neck tumors
- Salivary gland neoplasia
- Thyroglossal duct cyst
- Branchial cleft cyst
- Dermoid cyst
- Ectopic thyroid
- Thymic cyst
- Lymphadenopathy (may be viral or bacterial)
- Cat scratch
Evaluation of a patient with a neck mass should always begin with a thorough history, followed by a complete head and neck examination. The entire mucosal surface of the upper aerodigestive tract requires special attention. If the physical examination does not explain the neck mass, a fine-needle aspiration (FNA) of the neck mass may be performed. The results of the FNA may allow the physician to focus further testing. For instance, if the mass is found to be a metastatic squamous carcinoma, a thorough examination of the upper aerodigestive tract is warranted.
See 10 Patients with Neck Masses: Identifying Malignant versus Benign, a Critical Images slideshow, to help identify several types of masses.
FNA for cytologic evaluation of a neck mass was first reported by Kun in 1847. However, the procedure did not gain wide acceptance in medicine at that time. In the 1930s, Memorial Sloan Kettering rediscovered the utility of needle biopsy of head and neck masses. The use of large-bore needles at that time led to frequent complications, one of which was occasional seeding of the tumor along the biopsy tract. The frequent morbidity associated with this procedure prevented widespread acceptance of this technique in other centers of America. A resurgence of FNA occurred in the 1950s, led by physicians in Sweden. FNA was commonly used for cytologic examination of metastatic lesions in the neck with excellent results. Since then, FNA of solitary neck masses has become a well-accepted, safe, and cost-effective procedure in the diagnosis of neck masses.
FNA allows the pathologist to see the cells aspirated from the lesion. In contrast to large bore needle biopsy techniques, FNA does not allow evaluation of the morphology. In some instances, aspirated cells can be evaluated by flow cytometry or with immunologic markers. In every circumstance, FNA is a test and should be interpreted with the entire clinical circumstances. False-negative and false-positive FNA results are reported in almost every series. Therefore, reliance upon FNA findings at the expense of clinical, radiographic, or other findings is unsafe.
Advantages over open biopsy
Fine-needle aspiration (FNA) has several advantages over excisional biopsy. In today's economic environment, cost savings is an important consideration in medicine. The cost of FNA in the office varies from $75 to $350 depending on the study source and whether or not the pathology fees are included. In contrast, the cost of an excisional biopsy ranges from $1200-2500. The cost is even higher if a hospital stay is required.
FNA is also more convenient for patients and their families. The procedure requires only an office visit with minimal loss of time from work. On the other hand, excisional biopsy often requires time off from work, preoperative blood tests, and often, radiographic and cardiac testing. Furthermore, surgery exposes patients to the risks of anesthesia, postoperative infection, and the possibility of tumor seeding (see below). A percentage of patients may require overnight admission to the hospital and extra time away from work.
Open biopsy may interfere with further treatment. Incorrectly placed biopsy incisions may make subsequent neck dissection or excision difficult. In 1991, Birchall and colleagues demonstrated that 6 of 10 patients undergoing excisional biopsy of masses experienced complications in relation to the biopsy. These complications included compromise of later tumor resection, the necessity for excision of extra skin and adjacent soft tissue, and local recurrence in the neck wound after surgery.
Limitations of fine-needle aspiration
Fine-needle aspiration (FNA) for head and neck masses has several limitations. Failure to establish an accurate diagnosis may be because of sampling error. In these circumstances, repeat aspiration is suggested, and excisional biopsy may be considered. Personnel responsible for handling, processing (experienced cytotechnologist), and reading (cytopathologist) FNA samples must be well trained. Interobserver variability must be minimized. The accuracy of FNA varies with report and according to the tissues sampled (see specific examples below).
The diagnostic accuracy following aspiration of a cystic mass may be especially suspect because of the potential to aspirate acellular material. Good evidence currently suggests that the best results are achieved when FNA is accomplished using ultrasonographic or CT guidance to improve sampling accuracy. Either modality allows more precise localization of lesions and may facilitate more accurate positioning of the needle to aspirate the capsule in lesions with central necrosis. Accuracy is further enhanced by including a cytologist at the chairside to stain and preview the slides before the procedure is terminated. This also offers the potential to obtain extra material for flow cytometry when a lymphoma is suspected.
If any questions exist regarding interpretation of the aspirate, decisions on further therapy (eg, surgery, radiation, chemotherapy) should be deferred until the mass is accurately diagnosed. Finally, using FNA under the appropriate conditions is important. FNA complements clinical diagnosis and should not be considered a substitute for a thorough history and physical examination.
The neck is the part of the body that separates the head from the torso. The Latin-derived term cervical means "of the neck." The neck supports the weight of the head and is highly flexible, allowing the head to turn and flex in different directions.
The midline in front of the neck has a prominence of the thyroid cartilage termed the laryngeal prominence, or the so-called "Adam's apple." Between the Adam’s apple and the chin, the hyoid bone can be felt; below the thyroid cartilage, a further ring that can be felt in the midline is the cricoid cartilage. Between the cricoid cartilage and the suprasternal notch, the trachea and isthmus of the thyroid gland can be felt.
The quadrangular area is on the side of the neck and is bounded superiorly by the lower border of the body of the mandible and the mastoid process, inferiorly by the clavicle, anteriorly by a midline in front of the neck, and posteriorly by the trapezius muscle.
The image below depicts the anterior cervical muscles.
For more information about the relevant anatomy, see Neck Anatomy.
General results of fine-needle aspiration
As mentioned in the beginning of the article, interest in fine-needle aspiration (FNA) in the diagnosis of neck masses has increased. Scandinavian success with FNA has been replicated by several large American studies for the head and neck. In 1982, Frable and Frable reviewed the success of FNA in 567 patients with neck masses. Since then, multiple reports of experience with FNA in the diagnosis of head and neck lesions have been published. Sensitivity and specificity rates are approximately 85-90%. This means the incidence of false-negative and false-positive results range from 10-15%. FNA is not a substitute for excisional biopsy but should be considered an additional diagnostic tool to be used concurrently with patient history, physical findings, and laboratory tests.
Fine-needle aspiration in pediatric patients
Neck masses in children differ from those in adults. Children are far more likely than adults to have reactive lymphadenopathy. Primary or secondary malignant involvement is rare in children.
Unfortunately, the literature on FNA in children is limited by small study size and varying results. Stevens et al report a meta-analysis of FNA biopsy in pediatric thyroid nodules. They conclude it is a sensitive test and useful for excluding malignancy. A recent small study of 18 pediatric patients with cervical lymphadenopathy found FNA biopsy to have 100% sensitivity, 93% positive predictive value, and 94.5% accuracy for distinguishing malignancy from benign lymphadenopathy.
Selective results with fine-needle aspiration
Although fine-needle aspiration (FNA) may not be the method of choice for all neck masses, studies demonstrate a specific advantage of FNA for the diagnosis of several specific disease entities. In a study of metastatic squamous cell carcinoma of the neck subsequently treated by neck dissection, Knappe et al found that ultrasound-guided FNA had a sensitivity of 89%, specificity of 98%, and accuracy of 94%. In the event of the unknown primary squamous cell carcinoma of the head and neck, the predictive power of FNA allows physicians to narrow the search for the primary tumor. Furthermore, FNA can be a powerful tool for diagnosing cervical recurrence of head and neck squamous cell carcinomas without the financial costs and the morbidity of excisional biopsy.
More recently, FNA has been useful for detection of squamous cell carcinoma related to human papillomavirus (HPV). In a review of 70 patients who underwent FNA for squamous cell carcinoma, two thirds of the FNA specimens contained adequate DNA for molecular detection of HPV-related disease.
FNA biopsy for diagnosis of squamous cell carcinoma may have lower sensitivity in the event of a cystic mass or previous neck irradiation. Chan and Chan note that in patients who previously received radiation, the sensitivity of FNA was only 40%, compared with 82% in patients without prior neck irradiation. Gourin and Johnson report FNA results in 12 patients with cystic metastasis. False-negative aspirates were encountered in 5 (42%) patients. In each case, the diagnosis was made by excisional biopsy. The presence of a thick-walled cyst should raise clinical concern for this entity.
The prevalence of thyroid nodules detectable by ultrasound may approach 60-70% in the population.[11, 12, 13] Incidence varies by age and method of detection. Incidence of carcinoma in thyroid nodules is less than 10% in most populations.
Many studies have examined the use of FNA in the diagnosis of masses suspicious for thyroid malignancies. A recent study of FNA biopsy in nearly 2,000 patients at the Mayo Clinic showed a 97% positive predictive value and 92% negative predictive value for malignancy. Other reports support these data.[11, 14]
While thyroid nodules larger than 4 cm are more likely to be malignant, it is unclear whether FNA is less accurate for nodules of this size. A recent large study in over 1,000 patients showed no difference in sensitivity, specificity, or positive predictive value of FNA for nodules larger than 4 cm versus those smaller than 4 cm; negative predictive value was improved for nodules larger than 4 cm.
While papillary thyroid carcinoma can often be diagnosed with FNA based on classic cytologic features, follicular adenoma is difficult or impossible to distinguish from follicular carcinoma in most aspirates. The difficulty in distinguishing benign from malignant has led to the term follicular neoplasm. Because of the difficulty in differentiating follicular adenoma from well-differentiated follicular carcinoma with FNA, the presence of a follicular neoplasm with FNA is an indication for thyroid surgery. Recent investigations report that the use of molecular markers such as BRAF, galectin-3, HBME-1, PAX-8-PPARγ, RAS, and RET/PRC are gaining increasing clinical usefulness.[16, 17, 12, 18, 19]
Use of FNA for isolated salivary gland masses is broadly accepted. Nevertheless, surgeons are cautioned to interpret the result of FNA within the context of the clinical situation. Both false-negative and false-positive results are encountered. Interpretation of salivary gland pathology is difficult (the most common tumors are "pleomorphic" adenoma) and requires greater experience than the interpretation of some other neck masses.
In 2012, Tryggvason et al evaluated FNA biopsy in 543 patients with salivary gland masses, the majority involving the parotid gland, finding a sensitivity of 85.7% and specificity of 99.5% for identification of the final histologic diagnosis following surgical resection. Positive predictive value for malignancy was over 98%, while negative predictive value was 94.3%. In another 2012 study including 249 patients with parotid masses, FNA was found to be only 80% sensitive and 89.5% specific for the detection of malignancy. These results suggest that FNA alone may not be sufficient to rule out salivary malignancies and that further clinical evaluation, including surgical resection, may be necessary. Most reports acknowledge a low but important incidence of false-positive aspirates. When clinical suspicion warrants it, further sampling (eg, excisional biopsy) is appropriate.
When cytologic evaluation suggests a lymphoid lesion, further study may be essential to rule out lymphoma. Although FNA is 98% specific for the absence of tumor and 95% sensitive for the presence of tumor in most neck masses, improper diagnosis may be encountered when trying to distinguish lymphoma from reactive lymphadenitis.
The accurate cellular diagnosis of a specific lymphoma depends on changes in lymph node architecture, which requires morphologic examination of the entire node. However, when the previous cytoarchitecture of a lymphoma specimen is known, FNA is reliable in predicting recurrence.
Some reports have suggested that Hodgkin lymphoma can be accurately diagnosed by FNA. Hodgkin lymphoma is suggested by the presence of Reed-Sternberg cells in the setting of numerous lymphocytes on FNA. The role of FNA in the diagnosis of non-Hodgkin lymphoma is controversial. The diagnostic yield of FNA is low because differentiating non-Hodgkin lymphoma from lymphocytic thyroiditis and anaplastic thyroid carcinoma is difficult. Studies that combine FNA with flow cytometry and immunohistochemistry may increase the accuracy of lymphoma diagnosis without the need for excisional biopsies.
Flow cytometry uses a beam of laser light to identify cell surface antigens. Tagged antibodies bind to cell surface antigens on lymphocytes, allowing the identification of non-Hodgkin lymphoma. Recently, flow cytometry has been used to help diagnose pathology on FNA. In a recent 10-year study of over 500 patients by Savage and colleagues, flow cytometry was performed on FNA specimens to differentiate lymphoma from reactive lymphadenopathy, with results compared to histologic diagnosis from excisional biopsy or to prolonged follow up. The authors noted that flow cytometry had an accuracy of 88.4%, sensitivity of 85.8%, and specificity of 92.9%.
FNA is routinely used for the histologic diagnosis of isolated neoplastic neck masses. However, use of FNA in the diagnosis of inflammatory lesions has been limited. FNA could likely be used to isolate individual organisms or at least allow for the culture of an offending organism. An array of case reports and case series has demonstrated a use for FNA in the diagnosis of infectious diseases of the neck. A few of the causes identified include Staphylococcus aureus,Escherichia coli, and Bacteroides fragilis;Cryptococcus, Mycobacterium, Coccidioides,Bacteroides,Streptococcus,Haemophilus,Pseudomonas, and Citrobacter species; and Cytomegalovirus infection, syphilis, and actinomycosis.
Tuberculous lymphadenitis may manifest itself as a neck mass. FNA specimens have cytologic evidence consistent with tuberculosis, including granulomatous inflammation and/or caseation necrosis. Multiple recent studies have demonstrated greater than 90% accuracy in diagnosis of tuberculous lymphadenitis with FNA.[23, 24, 25]
See the list below:
If the physical examination does not explain the neck mass, a fine-needle aspiration (FNA) of the neck mass should be considered.
If the mass is believed to be a metastatic lesion, careful examination of the entire upper aerodigestive tract (eg, nasopharynx, larynx, hypopharynx) is warranted.
See the list below:
Fine-needle aspiration carries almost no absolute contraindications. If the physician is concerned about proximity to vital structures, guidance with computed tomography (CT) or ultrasonography (US) is available.
Coagulopathy is of some concern. As most FNA procedures are elective, efforts should be directed at correction of the coagulation defect. In patients who are anticoagulated, some reversal of the drug is usually done before the procedure.
In all cases, proper compression after the procedure is completed is essential.
See the list below:
See the list below:
A 21-gauge needle is commonly used. Larger needles may be used, but they involve a higher risk of complication and may result in contaminating the specimen with red blood cells.
Various custom syringe holders are currently available in the marketplace.
See the list below:
An important step in FNA is patient positioning. The patient is positioned to allow the most optimal digital palpation of the mass.
In the event the mass is not easily palpable, the physician should call upon either US or CT to improve diagnostic accuracy.
Fine-needle aspiration (FNA) is a simple office procedure that requires a few minutes to complete. It is ideal to have the cytotechnologist and pathologist available at the time of the aspiration. This allows an immediate assessment of the adequacy of the specimen. If insufficient cells have been obtained, the aspirate can be repeated. Sometimes the diagnosis can be made immediately.
The skin that overlies the mass is prepared with a prepackaged, sterile, alcohol preparation sponge that contains 70% isopropyl alcohol. For right-handed surgeons, the mass is grasped with the left hand and held in a fixed and stable position.
A 10-mL disposable syringe with an attached 21-gauge needle is placed just under the skin surface. Negative suction is applied to the syringe. The negative pressure is created and maintained by pulling the syringe plunger back. The mass is entered, and multiple passes are made without exiting the skin surface. Approximately 6 passes through the mass are recommended. If a cyst is encountered, it should be completely evacuated, with fluid sent for cytology. Recall that the cyst fluid may "dilute" the specimen and make cytologic interpretation impossible. Accordingly, aspirating the solid portions of the mass is ideal. The vacuum on the syringe is then released, and the skin is exited.
A small drop of aspirated fluid is placed on a glass slide, as shown in the first image below. A smear is made by laying another glass slide on top of the drop of fluid and pulling the slides apart to spread the fluid, as shown in the second image below. Wet smears are placed in 95% ethyl alcohol and treated with the Papanicolaou technique and stains. These stains offer excellent cellular detail and may indicate the cellular origin of a metastatic tumor. Specimens should be air dried and prepared for Wright-Giemsa stain when the differential diagnosis includes salivary, lymphoproliferative, and/or fatty tumors.
The following common technical errors lead to inadequate specimens:
Aspirating a mass without a syringe holder
Aspirating a mass without moving the needle back and forth through the specimen (to dislodge the cells)
Aspiration of air after the biopsy is completed and the needle is withdrawn, allowing the small specimen to be lost in the syringe
Other nontechnical errors of specimen collection include the collection of necrotic and/or fibrotic specimens.
Some debate exists about what constitutes an adequate specimen for cytopathological diagnosis by FNA. When aspirates are placed on slides, clusters of cells form. Clusters contain approximately 10 cells, and at least several clusters of 8-10 cells are needed for interpretation. In a 1997 review of FNA of breast masses, Layfield and colleagues indicated that FNA smears with 6 or more cell clusters decrease the false-negative rate to 2.1% and decrease the percentage of inadequate specimens to 13.7%. However, if slides that contain fewer than 6 clusters of breast tissue were excluded, 40% of true-negative and 4.5% of true-positive slides would be lost to analysis. The authors conclude that sampling adequacy should be based on the confidence of needle placement, cell preservation, and correlation with clinical findings.
The National Cancer Institute hosted a conference that resulted in terminology and criteria needed for diagnosis of thyroid lesions now widely employed by cytopathologists (The Bethesda System).
See the list below:
When the diagnosis is uncertain, an FNA can almost always help.
The results of FNA may contribute to establishing the diagnosis but should not be accepted as absolute when clinical or other information contradicts the FNA findings.
The accuracy of FNA is increased by providing the cytopathologist accurate clinical information. It may be further enhanced by having the pathologist chairside during the procedure, allowing for immediate pathologic confirmation of the adequacy of the specimen. Further passes can be undertaken when acellular yields are encountered. If the specimen suggests a lymphoproliferative process, a specimen can be obtained for flow cytometry.
The overall yield of FNA is enhanced with image guidance. The most common approach is to use ultrasonography; however, CT guidance is commonly used.
See the list below:
Complications of FNA are rare.
Hematoma and bruising are reduced with proper application of compression after the procedure.
FNA adjacent to vital structures or in deeply placed masses can be made more safe with the use of CT or US guidance.
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