Diagnostic Utility Of Modified Cell Block From Fine Needle Aspirates Of Thyroid Nodules At Kenyatta National Hospital, Kenya.

Abstract

Background: Fine needle aspiration cytology (FNAC) is a standard screening tool for the diagnosis and evaluation of thyroid nodules. It is a safe way of evaluating thyroid nodules. However this technique has some limitations such as false negative or positive results, high rate of unsatisfactory results and inability to classify border line lesions which result into indeterminate result. Objective: To describe the utility of modified cell-block as an adjunct test to FNAC in the diagnosis of thyroid lesions. Design: This study was a cross-sectional descriptive study. Subjects: A total of 52 cases suspected of clinically having thyroid lesions at Kenyatta National Hospital (KNH) FNA clinic were recruited. Setting: This study was done at Kenyatta National Hospital FNA clinic. Study Period: The study was conducted from February 2016 to April 2016. Methodology: FNA materials for both conventional smears (CS) and modified cell blocks (CB) were collected simultaneously from 52 patients suspected of clinically having thyroid lesions at KNH. All patients with thyroid lesions were included in this study and patients with a history of thyroidectomy were excluded. Ethical clearance was obtained from KNH/UoN Ethics and Research Committee before carrying out the study. Written informed consent was sought from all participating patients. Cellularity, morphological and architectural preservation, as well as cytologic diagnosis on CS was compared with CB sections. Data was entered on Microsoft excel and analyzed using SPSS software version 20. McNemar’s Chi-square statistical tests was performed at 95% confidence level. Results: Male to Female ratio was 1:8.7, (12%: 88%). Age ranged from 21 to 73 years with mean age of 41 and standard deviation of 13 years. This study showed that modified cell block preparations had high cellularity, minimal obscuring background material with excellent architecture compared to conventional smears. The majority (73.1%) of the thyroid FNA were reported as benign with a high unsatisfactory rate of 25%. The diagnosis of colloid goiter and xiv thyroiditis were picked up by both methods. Modified cellblock provided additional information for diagnosis of thyroid lesions in 15.4% of the total cases. Unsatisfactory rate of Thyroid FNA cytology was reduced from 25% to 13.4% when both methods were used thereby increasing the diagnostic efficacy to 86.6%. The diagnosis of Suspicious/follicular neoplasm which was missed on conventional smear was picked up by modified cell block preparation. Comparing the diagnosis on McNemar’s Chi square test, there was no statistically significant difference in the two methods (p-value >0.05). Conclusion: This study has not demonstrated statistically significant differences in the diagnostic utility of both methods, but modified cell block preparation provided additional information which was helpful in confirming and establishing new diagnosis. Recommendations: In resource constrained settings, the cost implications should guide in the selection of the method to use. Proper training and monitoring of clinician performing FNA procedure should be provided in order to reduce unsatisfactory results of the thyroid aspirates.