Endometrial glandular and stromal breakdown, part 2: cytomorphology of papillary metaplastic changes

Careful cytomorphologic evaluation of abnormal endometrial lesions has made accurate and reproducible microscopic assessment possible. Histopathology of patients with dysfunctional uterine bleeding due to an anovulatory cycle usually contain endometrial glandular and stromal breakdown (EGBD) and papillary metaplasia on the endometrial surface epithelium, if an appropriate sample has been collected. We often recognized abnormal cell clumps in the cytological smears with EGBD cases. They were composed of metaplastic cells, and some irregular small projection figures were observed from the margins of the cell clumps. We describe the quantitation of metaplastic clumps with irregular protrusions (MCIP) in endometrial endocyte samples. The current study presents the cytomorphological characteristics of the metaplastic changes recognized in EGBD cases. During a 7-yr period, 144 cases for which histopathological diagnoses were obtained following endometrial curettage, after collecting a direct endometrial sample using the endocyte. The material comprised 49 cases of normal proliferative endometrium (NPE) (patients aged 28-51, average 39.9), 32 cases of EGBD (patients aged 30-67, average 49.6), and 63 cases of endometrial hyperplasia without atypia (EH) (patients aged 35-65, average 47.7). The following points were investigated: (1) the occurrence of metaplastic cells; (2) the occurrence and the frequency of MCIP; and (3) the occurrence of MCIP that contains condensed stromal clusters. Metaplastic cells were seen in 93.8% of the EGBD cases. Cytomorphologic pattern identified with MCIP was 90.6%, and its frequency showed 16.1%. The occurrence of MCIP that contain condensed stromal clusters (93.1%) showed a strong association in comparison with other lesions, such as NPE and EH. Our data appear to indicate that the appearance of MCIP with condensed stromal clusters originated from the papillary metaplasia, which occurred on the endometrial surface epithelium. The cytologic observation of those cells may be a useful indicator for providing the nature of EGBD endometrium.