Statistically evaluate the role of CD56 and p63 in the diagnosis of PTC and differentiating them from PTC mimickers.

ABSTRACT: Introduction: The coastal belt of Kerala is known for its radiation hazard and the increased incidence of thyroid disorders including PTC. PTC, if it shows classical histology is easy to diagnose. However, a lot of benign or non neoplastic lesions mimic PTC and then the diagnostic dilemma arises, hence, the need for a specific marker to diagnose PTC. Aim and objective: With this background in mind this study was conducted to evaluate the usefulness of CD56 and p63 IHC markers as diagnostic tools for PTC. Materials and method: This was a descriptive study conducted over a period of 18 months in the Dept of Pathology at GTDMC, Alappuzha. 100 consequetive thyroidectomy specimens received in the Dept were included in the study. The exclusion criterion was all pure colloid goiters which never pose as mimics of PTC. The specimens were studied for morphology and IHC done as per protocol with CD56 and p63 markers. A positive membranous staining without a cytoplasmic staining in 10% or more neoplastic cell is considered as positive staining for CD56 and any nuclear staining is counted as positive for p63. The findings were analyzed and sensitivity, specificity, PPV and NPV were calculated for these markers. Results: There were 34 cases of PTC and 33 showed negative staining with CD56, giving a Sensitivity of 97.1%, Specificity of 88.9%, Positive predictive value of 82.5% and a Negative predictive value of 98.2%. With p63, Sensitivity was 37.1%, Specificity 92.2%, positive predictive value 72.2% And Negative predictive value was 72.8%.other malignancies obtained include, Hurthle cell Carcinoma and Follicular Carcinoma. Conclusion: Hence to conclude, a combined panel of CD56 and p63 is very accurate in diagnosing PTC and differentiating it from its mimickers. Key words: PTC mimickers, CD56, p63, thyroid neoplasm