Diagnostic utility of NPC2 and CD56 in thyroid lesions: an immunohistochemical study

Introduction The papillary thyroid carcinoma (PTC) is considered the most common form of thyroid cancer; its nuclear characteristics are the most diagnostic feature, but some of these characteristics may be found in other thyroid tumors, making its diagnosis a challenge. Aim Assess the diagnostic utility of NPC2 and CD56 in differentiating PTC from other thyroid lesions that share the same characteristics. Materials and methods Seventy tissue blocks representing benign (20 fibroadenoma and 10 nodular hyperplasia) and malignant thyroid lesions (30 PTC and 10 follicular carcinoma) were randomly selected for the current study. Institutional Review Board, Minya University has reviewed and approved the submitted research proposal “Approval No. 404/04/2021.” Results 51.4% of the various thyroid lesions under investigation have strong NPC2 expression. A significant association was found between NPC2 expression and histologic subtype (P<0.001), PTC versus non-PTC lesions (P<0.001) and patients’ sex (P=0.044). Regarding PTC patients, NPC2 was found to be highly expressed in 83.3% of cases, and a statistically significant association was found between NPC2 expression and pathological tumor stage (P=0.013). CD56 negative expressions were found in 48.6% of all the studied cases. A statistically significant association was found between CD56 expression and histologic subtype, benign versus malignant lesions and PTC versus non-PTC lesions (P<0.001, 0.001, and 0.001). CD56 negative expression was found in 86.7% of PTC cases. A statistically significant association was found between CD56 expression and site of lesion and lymph node metastasis in PTC cases (P=0.029 and 0.009, respectively). Conclusion NPC2 and CD56 can be useful immunohistochemical markers in differentiating PTC from other thyroid mimics.