A comparative study between cytological and histopathological findings in thyroid swellings in Erbil City.Introduction
Fine needle aspiration cytology (FNAB) is a safe, easy to perform. Economic and an accurate procedure used in the diagnosis of thyroid Lesions, particularly in the presence of cold nodule . Fine needle aspiration and cytology (FNAC) is a well established out-patient procedure used in the primary diagnosis of palpable thyroid swellings . FNAC gained acceptance in the UK and the USA in 1970s. Currently this technique is practiced world-wide and it is the investigation of choice in thyroid, breast, and lymph node swellings . The technique has been shown to be simple, safe and cost-effective. The limitations include false negative results, false positive results and a proportion of FNA results that are not obviously benign or malignant and fall into the indeterminate or suspicious group . Published data suggest FNA has an overall accuracy rate around 75% in the detection of thyroid malignancy . The aim of this study was to determine the accuracy of FNA cytology in detection of thyroid swellings in our surgical unit and to assess the correlation between preoperative cytodiagnosis and postoperative histopathological diagnosis. The application of this method in Iraq was not reported before. The following study was carried out in order to evaluate its practicality and effective-ness by using both cytological and his topthological examination.
Materials and methods
Fine needle aspiration cytology was performed using aspirate and non-aspirate techniques on each thyroid swelling. The cytological sample was assessed by a single consultant pathologist and was classified as inadequate, non-neoplastic, neoplastic, suspicious or indeterminate.
FNAB of the thyroid was performed on 378 patients (338 female and 40 male, the mean age was 35.5 years, with a range of 13-70 years) admitted to Erbil teaching Hospital with different thyroid lesions Between 2000-2003. All FNACs were carried out by either a surgical registrar or consultant surgeon Two techniques were used to perform FNAC; (1).
Aspiration technique when a 23-gauge needle was connected to a 10-ml syringe mounted on a syringe holder. Multiple needle passes were made within the lesion 3-4 times at varying angles and depths and with constant negative pressure (never emerging outside the skin). Before final withdrawal, the negative pressure was released prior to the needle emerging from the skin. The cytological material was transferred on to glass slides. (2) Non-aspiration technique a similar 23-gauge needle was passed into the lesion 3-4 times in the same the same manner except that negative pressure was not used. After withdrawal, the needle was connected to a 10-ml syringe containing air and cytological material was transferred on to slides. All patients subsequently had a thyroid resection and a definitive diagnosis was reached. FNAC and histology specimens were analyzed by a consultant pathologist.
The aspirated material then smeared on 2-4 slides, fixed in 95% ethanol and stained by papanicoloau and May-Grunwald Giemsa stains. The cytological findings were compared with the histological results whenever a biopsy was taken.
FNAC results were classified in to five groups: a) Inadequate (no diagnosis was made because of inadequate cellular material), b) Non neoplastic (including multinodular goiter, colloid goiter, thyroiditis), c) Neoplastic (papillary, anaplastic, lymphoma), d) Suspicious (suggestive/suspicious of neoplasm--follicular neoplasm), Indeterminate (no diagnosis made in spite of enough cellular material). Histology specimens were classified as non-neoplastic and neoplastic. Pre-operative FNAC results were then compared with the definitive histological diagnosis.
Results and discussion
The cytological diagnosis of 378 cases include, 340 cases benign, 10 cases suspicious,18 cases malignant, and 10 cases inadequate (Table 1);. The comparison between cytological and histopathological diagnosis was possible in 150 cases only who underwent subsequent thyroid surgery. 14 cases were malignant by cytological examination, confirmed hislopathologically as malignant, 132 cases were benign cytologically, by histopathological examination 130 cases were benign and two cases were malignant (false negative) figure 1A, B, 4 cases were suspicious cytologically, proved to be malignant by histopathology. Therefore the sensitivity was 90% the specificity was 100%, and the overall accuracy was 98.7% (table 2)
The nature of these lesions was as follows (Table 3). 118 cases diagnosed cytologically as colloid goiter, histopathologically as nodular colloid goiter, some cystic degeneration was found within the colloid goiter. 14 cases were diagnosed cytologically as benign follicular cells, histopathologically were diagnosed as follows: 2 cases microfollicular adenoma, 2 cases as lymphocytic thyroiditis 8 cases as diffuse hyperplaslic thyroid tissue and 2 cases as follicular carcinoma two cases were diagnosed cytologically as undifferentiated malignant cells histopathologically was diagnosed as malignant lymphoma. 12 cases were diagnosed cytologically as malignant cells, histopathologically were diagnosed as papillary carcinoma, 4 cases were diagnosed cytologically as suspicious cells, proved histopathologically to be papillary carcinoma (Fig.2A,B). There wasn't any complication encountered during the study.
Fine needle aspiration cytology is regarded as the gold standard initial investigation in the diagnosis of thyroid swellings . The technique is safe simple and quick with a low complication rate and helps to select people preoperatively for surgery .
Cytological study of FNAS of thyroid lesion from 378 patients showed a sensitivity of 90% and specificity of 100%. These where more or less similar to other studies done before and during the same period as shown in table 4. The percentage of malignant tumors diagnosis was 13, 3%, higher than that reported by Mustapha I.A. Khalil 3%, but similar to those reported by Haruna A. Nggada, Alhaji B. 13.7%.
The comparative study between cytological and histopathological diagnosis were in agreement in all the malignant cases where as in the benign 132 cases were diagnosed cytological as benign by histopathological examination 130 cases were benign and one was malignant(false positive), table 2.
From this study it can be concluded that FNAC may eliminate the need for major surgical procedure for the sake of the diseases particularly in the high risk patients who are good candidate for surgery 9.
This is especially when dealing with a chemosensetive or radiosensitive (e.g. malignant lymphoma, and undifferentiated small cell carcinoma) [10,11].
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False negative occurred in 4 cases were suspicious cytologically, proved to be malignant by histopathology, and this False negative results are expected particularly with small tumors and when there is associated degenerative or inflammatory change in adjacent thyroid tissue. Limitation of thyroid FNAC we faced in this study is that: Since there is a group of lesions which overlap benign and malignant features, for instance, the distinction between a cellular colloid goiter and a follicular lesion was impossible so such cases had been excluded from the study [12,13]. Two cases diagnosed cytologicaly as benign follicular cells while histopathological diagnosis revealed Follicular carcinoma as a result cytological diagnosis of follicular adenoma vs. carcinoma was not possible on FNA and diagnosis was dependent on histological assessment for capsular/vascular invasion . Another limitation of thyroid FNAC is the large number of inadequate spirates . Published data suggest inadequate sample ranges between 931% . In our study the inadequate sample rate was 13%. The most important factors include experience of the aspirator and the criteria used to define a satisfactory sample.
In the published data, the sensitivity and specificity of thyroid FNAC in detecting lesions ranges from 85-98%, and 88-100% respectively (Table 5)., The determinant factor for such a wide range of sensitivity, specificity and accuracy may be how the cytopathologists classify 'suspicious' as well as false positive and negative samples. Some authors include follicular lesion in malignant/neoplastic group, whereas others exclude them from the calculations. In our study sensitivity rate was low compared to others as three out of four (75%) 'Indeterminate' FNAC results were later found to have malignancy on histological examination. This was despite adequate number of cells (by definition) and suggests that the FNAC interpretation is operator dependent. Our positive and negative predictive values are comparable with published data (table 5).
FNAC is a simple, safe and cost-effective diagnostic modality in the investigation of thyroid disease with high specificity and accuracy. The suspicious and indeterminate results prove to be an area of uncertainty often resolved by diagnostic surgical resection. Fine needle aspiration cytology in this study had sensitivity, specificity rate of 90.0%, and 100.0% respectively for diagnosing different thyroid lesions.
FNAC is a very valuable and minimally invasive procedure for the preoperative assessment of patients with thyroid nodules the technique can be standardized and useful results obtained thereby minimizing unnecessary surgery
We wish to thank Professor Bdor A. Irym FRCPath. (London) Department of pathology -Mousl college of Medicine, Dr. Salah Abubaker (Board of pathology Iran) Senior lecturer, Department of pathology College of Medicine Hawler Medical University and all the surgeons of the Hawler Medical University Teaching Hospital and City Specialist Hospital for referring their patients to us for FNAC and tissue specimens for histopathological diagnoses.
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[17.] Razmpa, E., H. Ghanaati, B. Naghibzadeh, P. Mazloom and A. Kashfi, 2002. ACTA MEDICA IRANICA (The Journal of the Faculty of Medicine, Tehran University of Medical Sciences), 40: 3.
(1) Abdulqadir Maghded Zangana (2) Salah Abu-Bakir (3) Sherwan Ahmad Garota
(1) CABS-FICS-MD, professor, Head/Department of surgery,
(2) Assistant professor, Head/Department of Pathology.
(3) Lecturer in general surgery
Abdulqadir Maghded Zangana, CABS-FICS-MD, professor, Head /Department of surgery, E-mail: firstname.lastname@example.org
Table 1: Cytological findings in 378 Patients Cytological diagnosis Number of cases % of cases Benign 340 89.95 Suspicious 10 2.65 Malignant 18 4.75 Inadequate 10 2.65 Total 378 100 Table 2: Comparison between cytological and histological diagnosis Diagnosis categories Cytological Histopathological (case numbers) (case numbers) Benign 132 130 Malignant 14 20 Suspicious 4 -- Total 150 150 All suspicious cases in cytology were malignant in histopathology in addition to two cases of false negative Table 3: Cytological results of aspirated thyroid lesions compared with the histological findings. No. of cases Cytological diagnosis Histological diagnosis 118 Colloid goiter Nodular colloid goiter 2 Benign follicular cells Microfollicular adenoma 2 Benign follicular cells Lympnocytic thyroiditis 82 Benign follicular cells Diffuse follicular Undifferentiated hyperplasic with malignant cells Malignant lymphoma 12 Malignant cells Papillary carcinoma 4 Suspicious cells Papillary carcinoma 2 Benign follicular cells Follicular carcinoma 150 Total Table 4: Comparison between sensitivity and specificity of our study with other studies (17). Authors and years Sensitivity specificity Haruna A. Nggada, Alhaji B. Mussa, 2003 98% 100% E. Razmpa, H. Ghanaati, 2000 92.3% 88.1% Mustapha I.A. Khalil 2001 85% 88% The Present study 2003 90.0% 100.0%