Fine-needle aspiration: technique and smear preparation - includes patient information sheet

Author: David Lieu
Date: Feb 15, 1997

Fine-needle aspiration is a rapid, accurate and inexpensive method to obtain a tissue specimen for diagnosis of suspicious lesions. The number of fine-needle aspirations performed can be expected to increase in this era of cost-conscious medicine. However, an accurate diagnosis is highly dependent on the quality of the smears, adequate clinical information and the experience of the pathologist. The clinician must be able to perform this procedure skillfully and provide good smears. Fine-needle aspiration skills can be learned by using the techniques described in this article and by continued training and experience. The most important factors are immobilization of the mass, the use of very small fine needles, sampling both with and without aspiration, use of multiple passes with the needle, reaspiration of any residual mass after fluid drainage if a cyst is encountered, aspiration of the margins of large masses, the two-slide smearing technique and rapid fixation of smears. Finally, extensive clinical information must be supplied to the pathologist interpreting the smears.

Although more than 60 years have passed since Martin and Ellis first introduced fine-needle aspiration in the United States, fine-needle aspiration has only become commonly used as a diagnostic technique since the 1970s.[1,2] The number of fine-needle aspirations performed can be expected to continue to grow in this era of cost-conscious medicine. Many studies have shown that fine-needle aspiration is cost effective and accurate when compared with open biopsy in the management of both palpable and nonpalpable masses.[3,4]

In the United States, fine-needle aspiration is performed by both clinicians and cytopathologists, which has resulted in some "turf battles" about who should perform these procedures.[5,6] The highest success rates come with experience,[7,9] but the battle may be moot since only 1,214 of the 19,404 board-certified anatomic and clinical pathologists in the United States also are board-certified in cytopathology.[10] Successful use of the fine-needle aspiration technique requires practice and is not a technique that should be performed only once or twice a year.

With the anticipated growth in the number of fine-needle aspirations performed as a result of tighter cost control and with the limited supply of new cytopathologists, clinicians will be called on more often to become proficient in performing this procedure. Proper techniques for fine-needle aspiration and smear preparation take considerable practice to perfect.[2] The quality of a specimen obtained by fine-needle aspiration is of utmost importance to the diagnosis. A well-fixed, cellular smear is easy to interpret, while a hypocellular, poorly fixed or obscured smear is uninterpretable.

Goals of Fine-Needle Aspiration

The most common reason to perform a fine-needle aspiration is to obtain a tissue specimen for diagnosis of a mass. Fine-needle aspiration is less expensive, more rapid and less invasive than open biopsy. However, an accurate diagnosis by fine-needle aspiration requires an excellent smear, extensive clinical information and an experienced pathologist.

In the ideal setting, the accuracy of fine-needle aspiration may be over 90 percent and may rival that of frozen section.[11,12] A diagnosis of malignant neoplasm based on findings of fine-needle aspiration guides further evaluation and treatment. Negative smears from a clinically benign mass reassure the clinician about the safety of observation rather than excision. Biopsy or repeated fine-needle aspiration should be performed for a mass with a suspicious result on fine-needle aspiration, since the risk of neoplasia is increased. Fine-needle aspiration performed preoperatively, even if surgery is planned regardless of the findings, will help determine the specific type of procedure needed. It is not uncommon for the results of fine-needle aspiration diagnosis to be a surprise. For example, extensive lymphadenopathy may turn out to be metastatic carcinoma or tuberculosis rather than lymphoma.

Patient Selection

Three criteria must be satisfied when selecting patients to undergo fine-needle aspiration.[13] First, the needle must be directed at a specific target. This target must be palpable if the fine-needle aspiration is performed without imaging guidance. In general, masses 1 cm or larger (or easily palpable masses as small as 0.5 cm) can be successfully aspirated. Unlike exfoliative cytology, fine-needle aspiration is not a screening test.

Second, a specimen obtained by fine-needle aspiration must be interpreted in light of the clinical setting. Clinical information is more critical in interpreting a fine-needle aspiration than a tissue biopsy because of the limited sampling. Information should include age, sex, anatomic site, size of the lesion, pertinent history, clinical impression and relevant radiographic studies. It is critical to determine whether the findings of fine-needle aspiration explain the clinical findings. For example, in a 42-year-old woman with lumpy, tender breasts but no dominant mass and a negative mammogram, a fine-needle aspiration of the breast that shows a few benign ductal epithelial cells and adipose tissue indicates a benign nonproliferative breast lesion. The cytologic findings explain the clinical findings. The same smear in a 50-year-old woman with a hard, fixed 2-cm mass and a suspicious mammogram is inadequate for diagnosis because it does not explain the clinical findings. A repeat fine-needle aspiration or a biopsy is indicated. Adequate clinical information must be provided for correct interpretation of a fine-needle aspiration.

Third, a negative or benign result on fine-needle aspiration must be reviewed critically. If a specific benign diagnosis, such as fibroadenoma, pleomorphic adenoma or abscess is made and is consistent with the clinical impression, then it is most likely accurate. A nonspecific benign diagnosis, such as fibrous tissue, adipose tissue, lymphocytes or ductal cells, may leave the question unanswered. It is possible that a malignant mass was missed by the needle or that the mass was entered but diagnostic cells could not be dislodged. A repeat fine-needle aspiration or biopsy should be performed if the clinical suspicion for malignancy is high.

Patient Consent

Informed consent should be obtained before performing fine-needle aspiration. Patients should be advised that, although fine-needle aspiration is a very low-risk procedure, adverse effects such as hematoma formation and, rarely, infection can occur. The patient is also advised that a false-negative aspiration may occur as a result of limited sampling. Patients can be given an information brochure to read and a consent form to sign (Figure 1) before fine-needle aspiration is performed[14] (see the accompanying patient information handout).

[Figure 1 ILLUSTRATION OMITTED]

Patient Positioning

Lesions that are appropriate for superficial fine-needle aspiration include masses in the breast, thyroid, head and neck, lymph nodes and soft tissue. Palpable masses in the prostate, vagina, mouth and abdomen can also be aspirated. In general, the best position is one in which the lesion is most easily felt. The most common positions are summarized in Table 1.[13,15,16]

TABLE 1 Patient Position for Fine-Needle Aspiration

Site PositionBreast Supine with ipsilateral arm under headThyroid Supine with pillow between scapulas to extend neckNeck and Sitting with head turned to salivary expose mass glandAxilla Sitting with ipsilateral arm on the shoulder of aspiratorAbdomen SupineProstate LithotomyVagina Lithotomy

The use of a 10-mL syringe and a 10-mL syringe holder, such as a Cameco syringe pistol (Precision Dynamics, San Fernando, Calif.; telephone: 818-897-1111), is recommended because they are small enough to be held with one hand and large enough to drain most cysts (Figure 2). Larger syringes do not provide additional suction.[13] The use of a syringe pistol is highly recommended because it provides more uniform suction and makes it easier to move the needle back and forth in the mass.

[Figure 2 ILLUSTRATION OMITTED]

Aspiration Technique

[8.] Lee KR, Foster RS, Papillo JL. Fine needle aspiration of the breast. Importance of the aspirator. Acta Cytol 1987;31:2814.

[9.] Kocjan G. Evaluation of the cost effectiveness of establishing a fine needle aspiration cytology clinic in a hospital out-patient department. Cytopathology 1991;2:13-8.

[10.] The Official ABMS directory of board certified medical specialists 1996. 28th ed. New Providence, N.J.: Marquis Who's Who, 1995:ixxii,ixxix.

[11.] Suen KC. Cytology of head and neck tumors, liver, and pancreas. Clin Lab Med 1991;11:317-56.

[12.] Layfield LJ, Tan P, Glasgow BJ. Fine-needle aspiration of salivary gland lesions. Comparison with frozen sections and histologic findings. Arch Pathol Lab Med 1987;111:346-53.

[13.] Stanley MW. Fine needle aspiration of palpable masses. Boston: Butterworth-Heinemann, 1993: 5,59-122.

[14.] Abele JS, Miller TS. Implementation of an. outpatient needle aspiration biopsy service and clinic: a personal perspective. In: Schmidt WA, Miller TR, Katz RL, et al, eds. Cytopathology annual 1993. Baltimore: Williams & Wilkins, 1993:43-71.

[15.] Kline TS, Kline IK. Breast. New York: Igaku-Shoin, 1989:9-19.

[16.] Chen VS, Qizilbash AH, Young JE. Head and neck. 2d ed. New York: Igaku-Shoin, 1996:1-14.

[17.] Zajdela A, de Maublanc MA, Schlienger P, Haye C. Cytologic diagnosis of orbital and periorbital palpable tumors using fine-needle sampling without aspiration. Diag Cytopath 1986;2:17-20.

The Author

DAVID LIEU, M.D. is associate pathologist at Merrithew Memorial Hospital in Martinez, Calif., and assistant clinical professor of pathology at the University of California, Los Angeles, School of Medicine. He received his medical degree from the University of California, Irvine, College of Medicine and served an internship and residency in pathology at Los Angeles County-University of Southern California Medical Center, Los Angeles, and served a fellowship in cytopathology and fine-needle aspiration at UCLA Medical Center.

Address correspondence to David Lieu, M.D., Department of Pathology, Merrithew Memorial Hospital and Clinics, 2500 Alhambra Ave., Martinez, CA 94553.

The author thank Carol Appleton, photographer with the Department of Pathology at the University of California, Los Angeles, Medical Center, for assistance with the figures.

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