Pathological processes and pretreatment cytologic diagnosis of neuroendocrine carcinoma of the endometrium: addendum report of the Kansai Clinical Oncology Group/Intergroup study in Japan.

A previous retrospective study of a neuroendocrine carcinoma of the endometrium including 42 cases employed a central pathologic review to ensure the reliability of the findings. However, the pathological processes were not described in detail. In this study, we further analyzed these processes and the results of pretreatment endometrial cytology of neuroendocrine carcinoma. Of the 65 patients from 18 institutions registered in the study, 42 (64.6%) were diagnosed with neuroendocrine carcinoma of the endometrium based on the central pathological review. Thirteen of the 23 excluded cases conflicted from their original diagnoses: 5 (38.5%) were diagnosed with endometrioid adenocarcinoma, 5 (38.5%) with undifferentiated carcinoma, and 3 (23.1%) with carcinosarcoma. Immunohistochemical staining led to a change in diagnosis for 8 (61.5%) of the 13 cases. Pretreatment endometrial cytology was examined in 38 (90.5%) cases; 34 (89.5%) of these 38 cases were found, or suspected, to be positive. To ensure the selection of appropriate therapy and keeping patients correctly informed, it is important to distinguish neuroendocrine carcinoma from other similar histologic types. Endometrial cytology may help in the early detection of this disease.