Objective: To analyze the value and limitations of fine needle aspiration (FNA) cytology in a rural setting.
Study design: Prospective analysis of 1,196 FNA cytology results of superficial and deep masses from 1,088 patients in rural New South Wales, Australia, between September 1990 and May 1996. The FNA procedures were performed by palpation and image guidance using various-gauge needles and core biopsies as appropriate.
Results: FNA cytology results were analyzed, based on body organs and cytomorphologic findings. Breast, 450 (41%); thyroid, 152 (14%); superficial lymph nodes, 150 (14%); lung, 98 (9%); and liver, 55 (5%), made up the majority of the cases. The following general cytologic categories were used: nonrepresentative (inadequate), 39 (3.58%); benign, 662 (60.85%); atypical, 45 (4.13%); suspicious, 30 (2.76%); and malignant, 312 (28.68%). Clinical and histologic follow-up (core biopsies in 100 patients and histology of the atypical, suspicious and malignant cytologic categories in 387 patients) showed over 96% sensitivity for a diagnosis of malignancy, with about a 4% false negative rate and 99.04% predictive value of a malignant FNA diagnosis. The false positive rate in the cytologically malignant group of 312 patients was 0.96%. The breast, thyroid and lymph node fine needle aspirations were mostly benign. The great majority of deep organ fine needle aspirations were malignant. Atypical and suspicious FNA cytology, seen in both superficial and deep sites, was due to either technical difficulty in obtaining material or problems of interpretation (genuine cytologic overlap or inexperience). The radiologically suspicious cases with negative cytology were either reaspirated or subjected to surgical biopsy.
Conclusion: FNA cytology, when practiced in a multidisciplinary setting with direct involvement of pathologists, radiologists and clinicians, is an extremely accurate, well-tolerated, relatively noninvasive and low-risk test that obviates the need for surgical intervention in most benign conditions and disseminated malignancies. Therefore, by taking an active role with on-site assessment of the FNA material and discussion with radiologic colleagues, the cytopathologist could offer an FNA service comparable to surgical pathology in sensitivity and very similar to frozen section in specificity.