Tubal metaplasia of the endometrium with cytologic atypia: analysis of p53, Ki-67, TERT, and long-term follow-up.

Tubal metaplasia of the endometrium may occasionally display cytologic atypia (atypical tubal metaplasia) resembling serous carcinoma or endometrial intraepithelial carcinoma. Although atypical tubal metaplasia is presumed to be reactive or degenerative in etiology, its clinical significance is unknown. In this study, we investigated atypical tubal metaplasia in regard to its immunoexpression of p53, Ki-67, and human telomerase reverse transcriptase (TERT), and its long-term clinical outcome. A total of 63 cases of atypical tubal metaplasia and 200 cases of endometrial samples with typical tubal metaplasia were followed for a mean of 64 and 61 months, respectively. Of the 63 atypical tubal metaplasia cases, formalin-fixed, paraffin-embedded tissue sections from 16 cases were immunostained with antibodies to p53, Ki-67, and TERT. Sections from 13 cases of uterine serous carcinoma were also stained for TERT as control. After long-term follow-up, 5% of patients in the atypical tubal metaplasia group developed hyperplasia without atypia compared with 4% of patients in the control group (P=0.44), whereas 3% in the atypical tubal metaplasia group developed atypical hyperplasia or carcinoma compared with 2% in the control group (P=0.44). p53 immunoreactivity was either focal and weak or negative in all cases of both atypical and typical tubal metaplasia (P>0.05). Ki-67 immunoreactivity was present in 0-5% of cells in 94% of both atypical and typical tubal metaplasia (P>0.05). TERT immunoexpression was absent in all 16 cases of atypical tubal metaplasia, but present in all 13 cases of uterine serous carcinoma (P<0.0001). Our study indicates that atypical tubal metaplasia displays an immunostaining pattern similar to otherwise typical tubal metaplasia of the endometrium, and distinct from uterine serous neoplasms. The presence of atypical tubal metaplasia in endometrial samplings does not increase the risk of developing endometrial hyperplasia or malignancy.