Expression of metallothionein and nuclear size in discrimination of malignancy in mucinous ovarian tumors

Metallothioneins (MTs) are low molecular weight proteins that control cell proliferation via their metalloregulatory function. Several studies in vari ous tumors have shown their influence in determining response to chemothera py and prognosis. Because there has been no such study pertaining to ovaria n tumors, we investigated MT expression and nuclear size in mucinous ovaria n neoplasms (12 benign, 6 borderline, and 8 malignant). The percentage of M T-positive stained cells was significantly higher in the borderline than in the benign tumors, but lower than in the malignant tumors. Single layers o f cells in the borderline tumors showed mild immunostaining in 50% of the c ells and moderate staining in the remaining 50%, while 83.3% of cells withi n multilayered epithelium showed moderate to strong immunostaining. In the carcinomas, 87.5% of tumors showed moderate to strong staining in single-la yered epithelium and moderate to strong staining of all the cells in multil ayered epithelium. Morphometry measurements showed that the mean nuclear ar ea of cells in the carcinomas was significantly larger than in the borderli ne or benign tumors. The nuclear area of cells in the carcinomas with early recurrence or metastasis was also significantly larger than in carcinomas without recurrence or metastasis. It is concluded that MT protein expressio n and nuclear size are possible markers for the evaluation of the progressi on of malignancy in mucinous ovarian tumors.