Cyto-histomorphological Analysis of Thyroid Nodule

Abstract

Introduction: Thyroid nodules are a very common medical condition worldwide with varied prevalence depending on population under study and diagnostic modality. They can be noticed by the patient as a swelling or by clinician as palpable nodule or using radiological technique such as Ultrasonography (USG) or Computerised Tomography (CT scan). Fine Needle Aspiration (FNA) is a very important modality to differentiate benign from malignant lesions. However, there are many diagnostic challenges, and in many instances, a definitive diagnosis is only possible through histopathology. In this study, clinico-cyto-histopathological analysis of thyroid nodules was made and discordant cases in cytology were analysed. Aim: To study the cyto-histopathological analysis of thyroid nodules and to determine the accuracy of cytology to diagnose malignancy. Materials and Methods: This was a three-year retrospective study of thyroidectomy specimens with cyto-histological correlation at Aseer Central Hospital, Abha, Saudi Arabia from January 2017 to December 2019. FNA was ultrasound-guided. Smears were fixed in 95% alcohol solution and Papanicolaou (PAP), Haematoxylin and Eosin (H and E) staining was done. The tissues were fixed in formalin, sampled and processed in automated tissue processing units. Immunohistochemistry was done wherever required using CytoKeratin (CK) 19, Calcitonin, CD34, Thyroid Transcription Factor 1 (TTF1), Ki67. Statistical analysis was done with IBM for the SPSS software version 25.0 for Windows. Results: A total of 340 thyroidectomy specimens were received in three years. There were 265 females (78%) and 75 males (22%). Majority of patients (259 cases, 76.1%) were in 20 to 50 years of age. Colloid Goiter (CG) was the most common pathology (131 cases, 38.5%). Papillary Thyroid Carcinoma (PTC) was the most common malignancy with 98 cases (28.8%). Overall, Sensitivity of FNA in thyroid pathology in present study is 49.2%, Specificity is 84.2%, Positive Predictive Value (PPV) is 74.7%, Negative Predictive Value (NPV) is 63.5% and Diagnostic Accuracy (DA) of 67.2%. Conclusion: The current study throws light on various thyroid lesions among thyroidectomy cases in mountain region of middle-east, along with cytological correlation. The study found the FNA as a great tool for preoperative categorisation of thyroid diseases, though the overall sensitivity was low with significantly high false negative rate. This study recommends better FNA techniques to avoid suboptimal material and better imaging modality and its interpretation for exact localisation of FNA site. It also highlights the higher incidence of incidental microcarcinoma in surgical specimens, warranting its significance on follow-up.

Keywords

• diagnostic errors
• fine needle aspiration
• malignant lesions