The Significance of $p27^{KIP1}$, MIB-1, bcl-2 and p53 Expression in the Differential Diagnosis of Follicular Adenoma and Carcinoma of the Thyroid Gland

갑상선 여포상 선종과 암종의 감별진단에서 $p27^{KIP1}$, MIB-1, bcl-2, p53 발현의 유용성에 대한 연구

Objectives: The most important differential point of follicular carcinoma from adenoma is capsular invasion or angioinvasion of follicular cells. Serial sections for examination of levels of tumor margins are necessary to watch the invasion. However, the interpretation of capsular invasion or angioinvasion is sometimes not feasible on the routine staining of tumor tissue. The aim of this study is to evaluate the clinical significance of expressions of $p27^{KIP1}$, MIB-1, bcl-2 and p53 in differential diagnosis of follicular adenoma and carcinoma. Materials and Methods: 16 cases of follicular carcinoma and 26 cases of follicular adenoma were entered on study of immunohistochemical stains for $p27^{KIP1}$, MIB-1, bcl-2 and p53. In carcinoma cases, correlation between the above markers, patient's age, tumor size, infiltration pattern and metastasis was studied. Results: $p27^{KIP1}$ labelling index (LI) of follicular carcinoma and adenoma was $4.89{\pm}6.92$ and $14.52{\pm}9.17$, respectively, but there was no significant difference between adenoma and carcinoma (p=0.2560). MIB-1 LI of carcinoma and adenoma was $4.11{\pm}3.89$ and $0.80{\pm}0.75$, respectively, and MIB-1 LI was significantly higher in carcinoma (p=0.0000). bcl-2 expression was seen in 2(12.5%) of 16 carcinoma cases and 130(50.0%) of 26 adenoma cases, and bcl-2 expression rate was higher in adenoma than in carcinoma(p=0.014). In one adenoma and one carcinoma case, p53 expression was noted. In follicular adenoma with atypia compared to adenoma without atypia, lower $p27^{KIP1}$ LI, higher MIB-1 LI and lower bcl-2 expression rate were seen. In follicular carcinoma, MIB-1 LI was significantly higher in invasive carcinoma(p=0.045) and was relatively increased in tumors larger than 3.0cm, showing angioinvasion and distant metastasis. But $p27^{KIP1}$ LI was higher in cases over 40 years old(p=0.008) and with conspicuous capsular invasion. There were no positive correlations between expressions of MIB-1, bcl-2 and p53. Conclusion: MIB-1 labelling index and bcl-2 expression could be helpful for differential diagnosis of follicular adenoma and carcinoma, but p53 showed very low expression rate and no significance in differential diagnosis. $p27^{KIP1}$ labelling index reveals decreasing tendency in carcinoma compared with adenoma, MIB-1 LI was considered as a poor prognostic marker in follicular carcinoma, but $p27^{KIP1}$ LI was higher in carcinoma cases over 40 years old with showing conspicuous capsular invasion. Further study for the significance of $p27^{KIP1}$ labelling index in follicular neoplasms is necessary to evaluate diagnostic value of follicular carcinoma.