Anatomic Pathology / ADEQUACY ASSESSMENT OF THYROID FINE-NEEDLE ASPIRATION

Pathologists and cytotechnologists often provide immediate specimen adequacy evaluation of thyroid fine-needle aspirations (FNAs) to ensure that diagnostic material is obtained. We assessed the cost-effectiveness of this practice. All patients who had a thyroid FNA specimen accessioned at the Beth Israel Deaconess Medical Center, Boston, MA, during a 6-month period were included and divided into 2 groups: (1) with or (2) without immediate adequacy assessment. Specimen adequacy from each group was compared. The time spent to perform the adequacy assessment was recorded. Compared with group 2, group 1 had more specimens with diagnostic cellular material (67.2% vs 47.0%) and fewer specimens with suboptimal (23.3% vs 38.1%) or nondiagnostic cellular material (9.5% vs 14.9%) (P = .002). At the time of adequacy assessment, 98% (60/61) of the adequate specimens were obtained with 3 or fewer passes. The improved rate of diagnostic material was achieved at a cost of 220 minutes of cytologists’ time per additional diagnostic specimen compared with group 2. It may be most cost-effective to routinely obtain 3 passes and to perform immediate adequacy assessment under special circumstances such as repeated procedures. Fine-needle aspiration (FNA) biopsy of thyroid lesions has proven to be a safe, efficient, accurate, and cost-effective method of diagnosing thyroid lesions to reduce the number of thyroid surgeries.1,2 Endocrinologists principally use it as a triage procedure but might obtain a definitive diagnosis for certain thyroid lesions, such as papillary carcinomas and medullary carcinomas. Accurate diagnosis of the thyroid FNA biopsy specimen is dependent primarily on adequate cellular material for interpretation, although the presence of abundant colloid is a strong indication of benignity.3 One of the ways to ensure specimen adequacy is to perform an immediate assessment of the aspirated material at the time of the procedure. The literature on the effectiveness of immediate adequacy assessment of FNA biopsy specimens in general is controversial. While some authors have demonstrated favorable results,4-6 others have reported prolonged procedure time without a significant increase in the diagnostic yield.7,8 The literature on the specific cost-effectiveness for thyroid FNA biopsy is limited.8 We, therefore, analyzed our data to ascertain the cost-effectiveness of immediate specimen adequacy assessment for thyroid FNA biopsy. Materials and Methods At the Beth Israel Deaconess Medical Center (BIDMC), Boston, MA, endocrinologists, surgeons, and radiologists perform thyroid FNA biopsy with or without the aid of ultrasound guidance and with or without the presence of a cytologist. In addition, an endocrinologist, a surgeon, a radiologist, and a pathologist attend the biweekly Thyroid Nodule Clinic to which clinicians refer their patients with thyroid nodules. Anatomic Pathology / ORIGINAL ARTICLE Am J Clin Pathol 2004;121:64-69 65 65 DOI: 10.1309/XLNDTE289WAQYK0Y 65 © American Society for Clinical Pathology When a thyroid FNA biopsy is deemed necessary, the radiologist performs the procedure under ultrasound guidance and the pathologist provides an immediate adequacy assessment. A final diagnosis is made following evaluation of all submitted materials. The reports of all thyroid FNA biopsy specimens obtained at the BIDMC from July to December 2002 were obtained. The BIDMC Internal Review Board granted approval to review clinical data for the study. Computerized medical records for all patients were reviewed to determine whether the thyroid FNA biopsy was performed under ultrasound guidance and the number of passes recorded by the radiologist or clinician. The presence of a cytologist for specimen adequacy assessment was determined from the reports. We then matched our patients’ information with the database of all patients who attended the Thyroid Nodule Clinic during the study period to determine whether the thyroid FNA biopsy specimen was obtained at the Thyroid Nodule Clinic. When a cytologist (a cytotechnologist, a cytopathology fellow, or a cytopathologist) attends the procedure, 1 or 2 direct smears are made from each pass and are air dried and stained with the rapid Romanowsky method. The remainder of the aspirated material from each pass is placed in a container of CytoLyt solution (Cytyc, Boxborough, MA) to be later processed by the ThinPrep (Cytyc) method and stained with the Papanicolaou stain. The attending cytologist reviews the direct smears immediately and determines the adequacy of the specimen based on the number of cells and the amount of colloid present. The criteria for an adequate specimen admittedly varies somewhat among the cytologists. Generally, a specimen is considered adequate when several groups of at least a dozen follicular cells are present. The requirement of cellularity may be reduced if abundant colloid is noted. Each pass is considered separately. If the smear is considered adequate, the procedure is terminated. Otherwise, another pass is obtained and a similar protocol is followed for each aspirate until the specimen is considered adequate or the radiologist or clinician decides to stop the procedure for other reasons. The same or a different cytologist reviews the direct smears prepared at the time of the procedure in conjunction with the ThinPrep slide to make a final diagnosis. The procedure is the same whether the aspiration is done at the Thyroid Nodule Clinic or at other sites. For cases with specimen adequacy assessments done outside the Thyroid Nodule Clinic during the second half of the study period, the amount of time from the cytologist leaving the laboratory to returning to the laboratory was determined. When no specimen adequacy assessment is done, the aspirated material from each separately designated site is placed in a container of CytoLyt solution and submitted to the BIDMC Cytology Laboratory to be processed by the ThinPrep method and stained with the Papanicolaou stain. Some clinicians might choose to make direct smears by themselves and submit them with the material preserved in CytoLyt. Otherwise, the final diagnosis is made on the basis of a single ThinPrep slide unless ancillary studies are deemed necessary. We use 7 diagnostic categories in the laboratory, and each specimen is assigned a category with further description. The 7 categories are: (1) positive for malignancy (papillary carcinoma, medullary carcinoma, lymphoma, and anaplastic carcinoma), (2) “suspicious for” malignancy, (3) follicular lesion with indeterminate potential of malignancy (microfollicular neoplasm, Hürthle cell neoplasm, and follicular lesion with features suggestive of papillary carcinoma), (4) most probably benign follicular lesions (mixed microfollicular and macrofollicular lesion and macrofollicular lesion), (5) negative for malignancy, (6) suboptimal cellularity, and (7) nondiagnostic owing to virtual absence of follicular cells. We usually attempt to subcategorize specimens in the suboptimal cellularity category based on the limited material to suggest whether they represent a microfollicular lesion or a mixed microfollicular and macrofollicular lesion. The specimens with cyst contents only also are included in this category. For the purpose of the present study, diagnoses in the categories other than the nondiagnostic and suboptimal cellularity categories were combined and considered adequate for diagnosis. Specimens were divided into 2 groups: (1) those that had an immediate specimen adequacy assessment performed by a cytologist and (2) those that did not. The final diagnoses, number of passes to the extent we could determine, and clinical information for each group were compared. Comparisons also were made between cases with specimen adequacy determined at the Thyroid Nodule Clinic and those with specimen adequacy determined elsewhere. The statistical significance of any difference was determined by the Fisher exact test or χ2 for categorical data and by the MannWhitney test for numeric data.