Fine Needle Aspiration Cytology Of Thyroid Nodule(S): A Nigerian Tertiary Hospital Experience

摘要

Fine needle aspiration cytology (FNAC) of the thyroid has been used as an initial investigative procedure of thyroid nodule(s) in the Department of Histopathology, University of Maiduguri Teaching Hospital for 10 years (1995-2004). This study is aimed at evaluating our experience of FNAC and correlating with histologic diagnosis. A total of 69 patients with 51(73.9%) cases of benign, 18 (26.1%) cases of malignancy. There were four cases suspicious of malignancy, which were considered as malignant. The benign diseases include 34(49.3%) nodular colloid goiter; 6(8.7%) toxic goiter; 7(10.1%) follicular adenoma; 2(2.9%) cases each of Hashimoto's and subacute thyroiditis. The malignant cases were 10(14.5%) follicular carcinoma; 3(4.3%) cases each of medullary and papillary carcinomas, and 2 (2.9%) anaplastic carcinoma. The diagnostic accuracy is 94.2%, Sensitivity, 88.9%; Specificity, 96.1%; False Negative rate, 11.1% and false positive rate, 3.9%. In conclusion, FNAC of the thyroid nodule(s), is sensitive, specific, accurate and the initial investigation of thyroid diseases in our tertiary hospital. We therefore encourage our clinicians to embrace this investigative procedure in the management of our patients. Introduction Fine needle aspiration cytology (FNAC) is a well-established technique for pre-operative investigation of thyroid nodule(s)1. The technique is the most noninvasive, cost-effective and efficient method of differentiating benign and malignant thyroid nodules2,3. Many investigators have shown that fine needle aspiration cytology is the single most sensitive, specific and cost-effective method in the investigation of solitary cold thyroid nodule4,5. FNAC of the thyroid is gaining popularity among the pathologists and clinician in University of Maiduguri Teaching Hospital (UMTH). It is the initial investigation in the management of thyroid disease in our center. However, this study is aimed at evaluating our experience of FNAC and correlating the finding with tissue biopsy diagnosis of thyroid nodules. Materials And Methods This is a retrospective study of 69 diagnosed cases of thyroid nodule(s) in the University of Maiduguri Teaching Hospital (UMTH), Nigeria between the periods of January 1995 and December 2004 inclusive. The case notes were retrieved and information about the Age, Sex, Fnac and histological diagnosis were extracted. The duplicate copies of all histological reports and their corresponding original slides were reviewed. The data were analysed in simple statistical tables.During the period of study, all patients were referred by the surgeons to histopathology department for cytopathological diagnosis. A fine-needle was then introduced and the pathologists took the thyroid-swelling aspirate. Each of the patients had one or two aspirates obtained using a 10 ml plastic syringe fitted with a 23-25-guage disposable needle 1?inches long. The procedure took a fraction of a minute. The aspirated contents of the needle are expelled on to glass slides. Four slides smear were made, two were immediately fixed in 95% ethyl alcohol for about 30 minutes and the remaining two were air-dried and then fixed. The slides were stained with Haematoxylin and Eosin (H&E), and MayGrunwald Giemsa (MGG) stains respectively and examined with light microscope. The microscopic diagnostic interpretation includes:- Benign, Malignant and Suspicious. Results A total of 116 cases of cytopathology and 140 cases of histopathological diagnosis of thyroid nodules were independently made within the study period. Sixty-nine (54.4%) cases were recruited for this study, both had cytopathological and histopathological diagnosis and therefore recruited for this study while the remaining either had cytopathological or histopathological diagnoses were excluded from the study.Table 1 shows the histological types of thyroid nodule(s) with 51(73.9%) cases benign and 18 (26.1%) cases malignant. The benign diseases include 34(49.3%) nodular colloid goi