A case of ovarian endometrioid borderline tumor with squamous morules

—A morphological and immunohistochemical study—

Abstract

Background : Morulae are nodular structures found in endometrial-type glands formed by particular type of metaplastic squamoid epithelia. Morulae are considered as a hormonally regressed component of glandular epithelium. We report herein on a case of an ovarian endometrioid borderline tumor with abundant morulae.
Case : A 43-year-old female with a left ovarian tumor underwent laparoscopic salpingo-oophorectomy. The pathological diagnosis was an endometrioid borderline tumor with morulae. In immunohistochemistry, morular cells revealed strongly positive membranous CD10 staining and nuclear beta-catenin accumulation. Touch smear cytology showed cohesive clusters of morulae with glandular components. Isolated atypical cells were few, and necrosis was not observed.
Conclusion : Morulae are commonly observed in endometrial premalignant or low-grade glandular lesions. Cytologists and pathologists should be aware of the subsequent cancer risk of endometrial lesions with morulae.