Endometrial metaplasia: Correlation of histological and cytological specimens obtained from 103 cases undergoing hysterectomy for endometrial carcinoma

Objective: To assess the frequency of endometrial metaplasia in histological and cytological specimens from the same cases, and to determine the relationship between various types of metaplasia and clinicopathological findings. Methods: We reviewed 103 histological specimens diagnosed as endometrioid adenocarcinoma, in which endometrial smears had been obtained before surgery. We examined the correlation between the frequency of endometrial metaplasia occurring in association with carcinoma in both histological and cytological specimens. The categories of metaplasia were eosinophilic metaplasia, squamous metaplasia, mucinous metaplasia, ciliated cell metaplasia and others. We compared the incidence of endometrial metaplasia with the clinicopathological findings for each case. Results: Endometrial metaplasia was recognized in 90 (87.4%) of the histological and 80 (77.7%) of the cytological specimens of 103 specimens, with the respective frequency of subtypes as follows: eosinophilic metaplasia (36.0% and 43.7%), squamous metaplasia (70.9% and 68.0%), mucinous metaplasia (38.8% and 19.4%), ciliated cell metaplasia (22.3% and 2.9%) and others (11.7% and 0%). Mixed subtypes were seen in 58.3% and 41.7% of histological and cytological specimens, respectively. In histology, mucinous metaplasia was significantly more frequent in G1-G2 than G3 carcinomas (P = 0.0089). Ciliated cell metaplasia was significantly related to endometrial hyperplasia (P = 0.0068). In cytology, eosinophilic and mucinous metaplasia were significantly associated with G1-G2 cases (P = 0.0061 and P = 0.0385). Conclusions: Endometrial metaplasia was seen in 87.4% of the histological and 77.7% of the cytological specimens. Where routine endometrial cytopathology is practiced, it is important to understand the detailed histological and cytological features of these changes.