PITFALLS OF THYROID CYTOLOGY IN DUHOK-IRAQ
Background: The current study was undertaken to determine the validity of thyroid fine needle aspiration cytology (FNAC) in Duhok-Iraq to clarify its traded diagnostic errors locally and broadly.
Patients and Methods: All thyroid cytologic and histologic cases referred to Duhok Pathology Centers, between January 2013 and December 2016, were enrolled in this study. Cytologic findings were compared with their corresponding final histologic results. The validity parameters of cytology were assessed and cases showing cytologic and histologic non-conformance were re-evaluated to highlight the dependant cytologic pitfalls used locally and in the literature.
Results: Of 553 thyroid biopsies with 81.6% benign and 18.4% malignant, only 125 cases had preoperative diagnostic cytology and subsequent histologic final diagnoses. Of these, apart from 2 unsatisfactory cases, only 6 (4.9%) cytologic reports were proved not to be matched with their corresponding histologic results. The remaining 117 (95.1%) cases showed complete agreement between the two evaluation tests. Malignancy was predicted by cytology in 82.9%with a sensitivity of 94.3% and specificity of 95.5%. All the 6 unmatched cases were aspirated blindly with no image guide, 4 were false positive resulting in 3.2%false positive rate and 89.2% positive predictive value. The remaining unmatched 2 cases were false negative cytologies that gave 1.6% false negative rate and 97.7% negative predictive value. Cytologically, 5 (83.3%) unmatched smears, 4 false positive and 1 false negative, appeared in smears of lymphocyte-rich thyroid lesions, particularly Hashimoto’s. The false positive pitfalls comprised 2 over diagnosis of hypercellular smears showing some features of papillary carcinoma, 1 overestimation of the large cells with nuclear atypia as follicular carcinoma and 1 over diagnosis of lymphoid hyperplasia as lymphoma. On the other hand, low cellular smears with unclear atypical lymphoid cells underdiagnosed low grade MALT lymphoma and unobvious cytologic criteria missed the diagnosis of papillary carcinoma.
Conclusions: Lymphocyte-rich thyroid smears should be interpreted by experienced cytopathologists in the context of clinical, radiological and cytologic findings as suchcases may give certain cytomorphologic pitfalls that may decrease the cytologic validity. In suspicious cases, further tests should be justified to overcome the limitations and pitfalls of features when applied alone.
2. Cibas ES, Ali SZ. 2009. The Bethesda System for Reporting Thyroid Cytopathology. Thyroid.19:1159-65.
3. Sinna EA, Ezzat N. Diagnostic accuracy of fine needle aspiration cytology in thyroid lesions. Journal of the Egyptian National Cancer Institute. 2012;24:63–70.
4. Haberal AN, Toru S, Ozen O, Arat Z,u Bilezikçi B. Diagnostic pitfalls in the evaluation of fine needle aspiration cytology of the thyroid: correlation with histopathology in 260 cases. Cytopathology. 2008;20(2):103-8.
5. Raab SS, Vrbin CM, Grzybicki DM, Sudilovsky D, Balassanian R, Zarbo RJ, et al. Errors in Thyroid Gland Fine-Needle Aspiration. Am J ClinPathol. 2006;125:873-2.
6. Thapa PB, Shrestha D, Pradhananga JP. Correlation of fine needle aspiration cytology with histopathology findings in cases of thyroid lesions in Bir Hospital. Journal of College of Medical Sciences-Nepal, 2013;9(1): 23-29.
7. Sharma C. Diagnostic accuracy of fine needle aspiration cytology of thyroid and evaluation of discordant cases. Journal of the Egyptian National Cancer Institute. 2015; 27(3):147-53.
8. Cibas ES and Ali SZ. The 2017 Bethesda System for Reporting Thyroid Cytopathology. Thyroid Cytopathology. Thyroid. 2017;27(11):1341-6..
9. Al Maqbali T, Tedla M, Weickert MO, Mehanna H. Malignancy risk analysis in patients with inadequate fine needle aspiration cytology of thyroid. PLoS One.2012;7(11):e49078.
10. Baloch ZW, Virginia A. LiVolsiVA. Cytologic and architectural mimics of papillary thyroid carcinoma. Diagnostic Challenges in Fine-Needle Aspiration and Surgical Pathology Specimens. Am J ClinPathol 2006;125: S135-S144.
11. Al-HroutM , Abu-Ala’sh O , JalabnehT, Al-Na’san W. Diagnostic value of fine needle aspiration cytology of thyroid nodules: Experience at King Hussein Medical Center. JRMS. 2015;22(3):59-63.
12. Basharat R1, Bukhari MH, Saeed S, Hamid T. Comparison of fine needle aspiration cytology and thyroid scan in solitary thyroid nodule. Patholog Res Int. 2011;2011:754041.
13. Mahar SA, Husain A, Islam N. Fine needle aspiration cytology of thyroid nodule: Diagnostic accuracy and pitfalls. J Ayub Med Coll Abbottabad. 2006;18:26-9.
14. Ko HM1, Jhu IK, Yang SH, Lee JH, Nam JH, Juhng SW, Choi C. Clinicopathologic analysis of fine needle aspiration cytology of the thyroid. A review of 1,613 cases and correlation with histopathologic diagnoses. ActaCytol. 2003;47(5):727-32.
15. Tabaqchali MA, Hanson JM, Johnson SJ, Wadehra V, Lennard TW, Proud G.Thyroid aspiration cytology in Newcastle: a six year cytology/histology correlation study.Ann R CollSurg Engl. 2000;82(3):149-55.
16. Saldanha P, Tak HN. Pitfalls in the diagnosis of fine needle aspiration cytology of the thyroid. IJBR. 2014;05 (12). DOI: https://doi.org/10.7439/ijbr.v5i12.823.
17. Jayaram G, Orell SR. Thyroid. In: Orell SR, Sterett GF, eds. Orell&Sterrett’s Fine Needle Aspiration Cytology. Churchill Livingstone, Elsevier, China, 2012: 118-55.
18. Hyeon J, Ahn S, Shin JH, Lyun Oh Y. The prediction of malignant risk in the category “atypia of undetermined significance/follicular lesion of undetermined significance” of the Bethesda System for Reporting Thyroid Cytopathology using subcategorization and BRAF mutation results. Cancer Cytopathol. 2014;122:368–376.
19. HafezNH, Tahoun NS. Reliability of fine needle aspiration cytology (FNAC) as a diagnostic tool in cases of cervical lymphadenopathy. Journal of the Egyptian National Cancer Institute. 2011;23(3): 105-14.
20. Pandey P, Dixit A, Mahajan NC. Fine-needle aspiration of the thyroid: A cytohistologic correlation with critical evaluation of discordant cases. Thyroid Res Pract 2012; 9:32-9.
21. Condel JL, Jukic DM, Sharbaugh DT, et al. Histology errors: use of real-time root cause analysis to improve practice. Pathol Case Rev. 2005;10:82-87.
22. Raab SS, Andrew-Jaja C, Condel JL, et al. Improving Papanicolaou test quality and reducing medical errors by using Toyota Production System methods. Am J Obstet Gynecol. 2006;194:57-64.
23. Geisinger K, Stanley MW, Raab SS, et al. Thyroid gland fine needle aspiration. In: Modern Cytopathology. Philadelphia, PA: Churchill Livingstone; 2004:731-780.
24. Geisinger K, Stanley MW, Raab SS, et al. Thyroid gland fine needle aspiration. In: Condel JL, Jukic DM, Sharbaugh DT, et al. Histology errors: use of real-time root cause analysis to improve practice. Pathol Case Rev. 2005;10:82-87.
25. Kocjan G. Cytological and molecular diagnosis of lymphoma. J ClinPathol. 2005;58:561-7.