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Updated: Aug 16, 2026

An Ex Vivo Model of Ovarian Cancer Peritoneal Metastasis Using Human Omentum
Published on: January 26, 2024
Decidualization of ovarian endometriosis during pregnancy mimicking malignancy
Rami N Sammour1, Zvi Leibovitz, Israel Shapiro
1Department of Obstetrics and Gynecology, Bnai-Zion Medical Center, PO Box 4940, Haifa 31048, Israel.
Objective:
The purpose of this series is to present deciduosis (the formation of extrauterine decidua) as one of the differential diagnoses of a malignant tumor during pregnancy.
Methods:
Two cases are described in which pregnant patients had a pelvic tumor. The lesions, which were diagnosed in the early second trimester, consisted of complex masses with an extensive blood supply and had a sonographic appearance of a malignant tumor. The high suspicion for malignancy necessitated surgical intervention.
Results:
During surgery, the lesions were observed to be of an ovarian origin with papillary excrescences covering their exterior. The lesions were excised and sent for histologic examination. The results showed a markedly decidualized endometriotic cyst in both cases.
Conclusions:
This phenomenon is a diagnostic challenge and should be considered in the differential diagnosis of a malignant mass during pregnancy.
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