Diagnostic role of immunohistochemical markers CK19 and CD56 in thyroid neoplasms

Introduction: Thyroid cancer is the most common type of endocrine cancer, with an increasing prevalence. The possibility of a malignant neoplasm is the primary concern in people with thyroid nodules. The presence of a plethora of variants complicates the diagnostic process. Cytokeratin 19 (CK19), found in normal thyroid follicular epithelium, is upregulated during neoplastic transformation, and CD56, a neural cell adhesion molecule, is downregulated in thyroid follicular cells. This study suggests the use of CK19 and CD56 in combination will help differentiate thyroid neoplasms. Materials and Methods: Total/hemithyroidectomy specimens received in the Department of Pathology, Maharaja Krushna Chandra Gajapati Medical College and Hospital, Brahmapur, Odisha, India, suspected of malignancy, were processed for routine histopathological evaluation using hematoxylin and eosin (H&E) stain and immunohistochemistry (IHC) staining using CK19 and CD56. The outcomes of each case were recorded and analyzed. Results: A total of 36 cases were evaluated, and the expression of CK19 was found to be 88% sensitive and 79% specific in differentiating malignant from benign thyroid neoplasms. The absence of CD56 expression was found to have 82% sensitivity and 74% specificity in detecting malignant thyroid neoplasms. The combined use of both markers has a sensitivity and specificity of 70.59% and 78.95%. Conclusion: The routine use of CK19 and CD56 by IHC will aid in distinguishing benign from malignant thyroid neoplasms.