Background and Objective: Thyroid cancer is the most common endocrine malignancy. The most common well-differentiated form of thyroid cancer is papillary carcinoma (PTC). Few studies on determining the role of CD10 in PTC prognosis have been performed, furthermore they have been controversial. This study was designed to determine the correlation of CD10 expression with age, gender, tumor size, lymph node involvement and capsular invasion as prognostic factors of PTC.

Materials and Methods: This study was a cross-sectional descriptive-analytic study. Data concerning age, gender, tumor size and lymph node involvement were derived from the medical records of 85 patients diagnosed with PTC that underwent thyroidectomy in Mostafa Khomeini Hospital between 2011 and 2014. With the help of four micrometer sections made from paraffin embedded blocks, CD10 expression was assessed by immunohistochemistry. Another section was stained with Hematoxylin & Eosin and capsular invasion was evaluated by light microscope.

Results: In this study 88.24% of patients were female and 11.76% were male. 41.2% of samples were CD10 positive. A significant correlation between CD10 and tumor size, lymph node involvement and capsular invasion was found. There was no significant correlation between CD10 expression and the age or gender of patients.

Conclusion: CD10 oncoprotein expression is correlated with increased tumor size, lymph node involvement and capsular invasion. Therefore CD10 can be used to assess PTC prognosis.