Fine Needle Aspiration Biopsy

The accuracy of fine needle aspiration biopsy (FNAB) in the diagnosis of salivary tumors has been well established. During the past 5 years, several studies from various countries have reported an exceptionally high degree of sensitivity and specificity. Examples of such studies are summarized in Table 66-1. The overall sensitivity ranges from 85.5% to 99%, and the overall specificity ranges from 96.3% to 100%.1-6 Diagnostic accuracy depends greatly on the experience of the cytopathologist, which in turn depends on the overall volume of patients with salivary neoplasms evaluated in any given institution. The reported sensitivity and specificity were slightly lower in community hospitals than at large academic centers.7 The most common source of diagnostic error is inadequate sampling. Among 582 FNABs of major and minor salivary glands, lack of cytologic and histologic correlation was noted in 21 cases. Of these, the cause in 10 FNABs was inadequate cytologic sampling of the lesion.8

In addition to being accurate, FNAB is safe, simple to perform, and relatively inexpensive. However, one essential question is worth asking. Is FNAB really necessary in the evaluation of parotid masses? Would it change the course of management based on clinical assessment? In an attempt to answer this question, Heller et al.9 performed a study to determine the impact of FNAB on patient management. In this study, 101 patients underwent FNAB of the major salivary gland masses. The physician's initial clinical impression was compared with the FNAB diagnosis and the final diagnosis in each case. Overall, FNAB prompted a change in the clinical approach to 35% of patients. Examples of such changes in the planned management included avoiding a relatively large resection for lymphomas and sialadenitis. FNAB leads to better informed preoperative counseling of patients, alleviating an already high level of anxiety both to them and to their families.2 On the

TABLE 66-1

Sensitivity and Specificity of Fine-Needle Aspiration Biopsy

TABLE 66-1

Sensitivity and Specificity of Fine-Needle Aspiration Biopsy

Study/Year

Country

Total Patients

Patients with Malignancy

Sensitivity %

Specificity %

Orell1 (1995)

Australia

325

85.5

99.5

Candel et al.2 (1993)

USA

163

15

95.7

100

Roland et al.3 (1993)

UK

92

90.9

100

Bhatia4 (1993)

India

101

34

99

100

Chan et al.5 (1992)

Hong Kong

112

36

86

99

Abad et al.6 (1992)

Spain

97

18

90

96.3

basis of these findings, the performance of FNAB may be helpful in treatment planning for patients who present with parotid

masses.

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