Morphologic features of endometriosis in various types of cytologic specimens.

Endometriosis is defined as the presence of endometrial tissue outside the uterine cavity. This study evaluates the cytomorphologic features of endometriosis in various cytologic specimen types [fine-needle aspiration (FNA), effusion cytology (EF), touch imprint (ToP), and cervical smear (PAP)], and assesses the key elements helpful in recognizing this lesion. A total of 18 cases (8 FNA, 4 EF, 5 ToP, and 1 PAP) of cytologically diagnosed and histologically/clinically confirmed endometriosis diagnosed between 1988 and 2006 comprises the material for this study. The morphologic features evaluated of the three components included: cellularity, presence of sheets of glandular cells, three-dimensional (3D) glandular clusters, tubular structures, single cells, syncytial groups of stromal cells, stromal cells entrapped within basement membrane (BM)-like material, cytologic atypia, presence of mitotic figures, and hemosiderin-laden histiocytes. Endometrial glands, stroma, and hemosiderin-laden histiocytes were all identified in 14/18 (77.8%) cases. FNA specimens were more cellular than that of both EF and ToP specimens. Tubular structures, 3D glandular clusters, stromal cells entrapped in BM and syncytial stromal groups were more common in FNAs, and ToPs compared with the EFs. The ratio of the endometrial glandular and stromal cells was similar in all specimen types. Atypia and mitotic figures were rarely encountered. Diagnosis of endometriosis could be made independently on either smears/ThinPrep(™) slides or on cell blocks in all cases where these preparations were available. On follow up, none of the patients developed malignancy. Endometriosis can be reliably and safely diagnosed in various cytologic materials. Cytologic atypia is uncommon. Components of endometriosis could show minor morphologic alterations in different specimen types.