Rasi, Raja Zubaidah Raja Mohd
(2017)
Accuracy of thyroid fine needle aspiration cytology by using bethesda system : a hospital based study.
Masters thesis, Universiti Sains Malaysia.
Abstract
Aim: In Hospital University Science of Malaysia, The Bethesda System of
Reporting Thyroid Cytology (TBSRTC) was not widely used by pathologist or
surgeon/clinician. Instead, conventional reporting system was used and the
result was not given tiered classification as in TBSRTC. This study is a
retrospective study to review all thyroid FNACs with histopathological
correlation in 5 years (2010 to 2014) base on Bethesda System and to look for
the accuracy as well as sensitivity and specificity.
Methods: We identified total of 563 thyroid FNACs cases performed from
January 2010 till December 2014 in Hospital Universiti Sains Malaysia (HUSM),
a teaching hospital in Kelantan, which form our study population. All cases were
identified from the database of Laboratory Information System (LIS) in the
Department Pathology, HUSM. After excluding the cases with exclusion criteria,
total of 110 FNAC cases were included in this study. These cases were thyroid
FNAC with good quality of slides and with histopathology examination (HPE)
result. Primary investigator, a pathologist and a cytopathologist reviewed all
slides from 110 cases and consensus diagnosis was given using TBSRTC.
SPSS version 20.0 is used for data entry and analysis. Descriptive statistic is
used for socio demographic data. Stata software is used for p-value by usingFisher Exact test for objective number 2. Statistic formulas are used to calculate
the accuracy, sensitivity and specificity.
Results:The patients age were range from 11 to 80 years. The mean age of the
patient included in this study was 44.70+/-14.52 (mean+/-SD) years. There
were 94 or 85.5% female and 16 or 14.5% male patients. Among 110 cases
which were reviewed using TBRSTC, 78 cases or 70.9% were reported as
benign on cytology, 1 case or 0.9% was reported as Atypia of Undetermined
Significant (AUS), 9 cases or 8.2% were reported as follicular neoplasm, 9
cases or 8.2% were reported as suspicious of malignancy and 13 cases or
11.8% were reported as malignancy. Cyto-histopathological correlation shows
29 cases or 26.4% were true positive, 75 cases or 68.2% were true negative, 3
cases or 2.7% were false positive and 3 cases or 2.7% were false negative.
Histopathological examination shows, 25 cases or 22.7% were malignant and
85 cases or 77.3% were benign. Among female patients, 76 cases or 81% were
benign and 18 cases or 19% were malignant histologically. Whereas, among
male patients, 7 cases or 44% were benign and 9 cases or 56% were malignant
histologically. 18 cases or 66.7% of malignant cases were female and 9 cases
or 33.3% of malignant cases were male. 76 cases or 91.6% of benign cases
were female and 7 cases or 8.4% of benign cases were male.
Cyto-histopathological correlation shows 96.2% benign and 3.8%
malignant in Bethesda II (benign), 100% malignant in Bethesda III (Atypia of
Undetermined Significant/Follicular Lesion of Undetermined Significant), 55.6%
benign and 44.4% malignant in Bethesda IV (follicular neoplasm), 33.3% benign
and 66.7% malignant in Bethesda V (suspicious malignancy) and 100%malignant in Bethesda VI (malignant). Statistically, the overall accuracy of
thyroid FNAC by using Bethesda System is 94.5%, the sensitivity is 90.6% and
the specificity is 96.1%. The positive predictive value is 90.6% and the negative
predictive value is 96.1%. By looking at each categories, benign (category II)
had 96% accuracy, AUS (category III) had 100% accuracy, follicular neoplasm
(category IV) had 100% accuracy, suspicious of malignancy (category V) had
66% accuracy and malignancy (category VI) had 100% accuracy.
Conclusion: From this study, we conclude that FNA is the most accurate and
cost effective method for evaluating thyroid nodule. This study also concludes
that The Bethesda System of Reporting Thyroid Cytology have high accuracy,
sensitivity and specificity. This system also can increase the accuracy in
malignant category.
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