Diagnostic pitfalls in the evaluation of fine needle aspiration cytology of the thyroid: correlation with histopathology in 260 cases

Abstract

Diagnostic pitfalls in the evaluation of fine needle aspiration cytology of the thyroid: correlation with histopathology in 260 cases Objectives: Fine needle aspiration cytology (FNAC) of the thyroid is a non-invasive, cost-effective screening procedure that is valuable for distinguishing neoplastic lesions from non-neoplastic nodules. The aim of this study was to determine the diagnostic accuracy of FNACs performed at our institution by correlating FNAC results with histopathological diagnoses. Methods: Two hundred and seventy-one aspiration cytology specimens followed by thyroidectomy were included in the study, and the results of 260 adequate FNACs were compared with their histological diagnoses. Results: The sensitivity and specificity of thyroid FNAC for detecting neoplasia were 92.6% and 91.6%, respectively. There were 15 (5.7%) false positives and six (2.3%) false negatives. Conclusions:The results showed that follicular cells that exhibit some of the features of papillary carcinoma could be observed in a cytology slide of HashimotoÕs thyroiditis, leading to a diagnostic pitfall. In addition, cellularity and overlapping cytological criteria in hyperplasia might lead to a false diagnosis.Keywords: diagnostic pitfalls, fine needle aspiration cytology, thyroid gland, cytodiagnosis, sensitivity, specificity Clinically detectable thyroid nodules occur in approximately 4-10% of the population; however, only 5-30% of the nodules are malignant, and a distinction between benign and malignant lesions is not easy to make on clinical presentation alone.1,2 The main goal of thyroid fine needle aspiration cytology (FNAC) is to identify the nodules that require surgery and decrease the overall incidence of thyroidectomy in patients with benign disease. However, there are some difficulties and limitations of diagnosis with FNAC, in that both false-negative and false-positive results can occur. 3 The most significant difficulty in making a diagnosis is the overlapping features of different lesions such as nodular goitre and follicular neoplasms. 1The current study was undertaken to evaluate the correlation between thryoid FNAC and histology and to determine the sources of diagnostic errors. MethodsBetween 1996 and 2005, 4352 thyroid FNACs were evaluated at Bas¸kent University and were subsequently reviewed. A total of 271 aspirations followed by thyroidectomy were evaluated and the cytology compared with the final histological diagnoses. Histological sections were evaluated in a multidisciplinary setting together with the review of the previous FNAC results. FNACs of thyroid were reported by only four pathologists, whereas seven pathologists, including these four, reported surgical specimens in our institute. All of the thyroid FNACs performed at Bas¸kent University were carried out under ultrasound (US) guidance [Hitachi, EUB 6500; Hitachi Medical Systems (S) Pte Ltd, Singapore] by a radiologist. Linear transducers, ‡ 7.5 MHz in frequency, were

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“…Most studies presented the incidence of HT in surgically resected PTC cases. In cytology specimens of HT patients, follicular cells often exhibit nuclear elongation, nuclear grooves, and even intranuclear inclusions, leading to a misdiagnosis of PTC (45,46). Therefore, the current meta-analysis included only the studies that presented cases of HT confirmed by histopathologic diagnosis.…”

The Credibility of Fine-Needle Aspiration Biopsy for Malignancy in Patients with Hashimoto Diseases

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