Cytologic features of atypical polypoid adenomyoma of the endometrium: A case report

In 1981, Mazur reported the histologic characteristics of atypical polypoid adenomyoma (APA) of the endometrium. Although most APAs of the endometrium are considered to show benign behavior, there is a small associated risk of the development of adenocarcinoma. The histology of APA of the endometrium is well defined, but the cytologic features of the lesion have not yet been clarified. A 28-year-old nulligravida with hypermenorrhea had an exophytic, polypoid mass arising from the posterior uterine wall on ultrasonography and magnetic resonance imaging. The results of endometrial smear and biopsy were normal. Transcervical total resection of the tumor was performed with a resectoscope. Frozen sections of the sample suggested APA of the endometrium, and the permanent sections confirmed the diagnosis. The tumor stump/resection plane smears revealed overlapping, highly atypical glandular cells with enlarged, hyperchromatic nuclei; squamous metaplastic cells; and abundant, spindled smooth muscle cells on a clear background, effectively reflecting the epithelial and mesenchymal cell components of the lesion. Endometrial smear and biopsy are inaccurate methods for the diagnosis of APA of the endometrium because of limited sampling. Tumor stump/resection plane cytology appears to be useful for detecting APA of the endometrium.