Endosalpingiosis in peritoneal washings in women with benign gynecologic conditions: Thirty-eight cases confirmed with paired box-8 immunohistochemical staining and correlation with surgical biopsy findings

BACKGROUND: To better define the cytomorphologic spectrum of endosalpingiosis in peritoneal washings (PWs) and thereby facilitate their distinction from well differentiated serous carcinoma, the authors examined PWs from women who underwent surgery and pathologic staging of lesions other than Mullerian malignancies and correlated the findings with surgical specimens. METHODS: This was a retrospective review of medical records and PW specimens from 100 consecutive patients who had PWs coded as both " endosalpingiosis" and "negative for carcinoma" between 2002 and 2012. Thirty-eight of these patients had no gynecologic malignancies. Specimens had been prepared using cytocentrifugation and were stained using the Papanicolaou method. The cytologic findings evaluated were cell arrangement, number of cell groups per case, cellular atypia, and psammoma bodies. Smears also were assessed for paired box-8 (PAX8) immunostaining. The authors compared patients' staging biopsy findings with the findings from a review of the PWs. RESULTS: PW specimens from 35 of 38 patients (92%) exhibited classic endosalpingiosis features: tubular or small branching papillary structures, some with psammoma bodies. Specimens from the 3 remaining patients displayed nonclassic features consistent with dislodged fallopian tube epithelium or endometriosis. From 2 to 20 clusters per slide and from 4 to 50 groups per case were identified. In a few cases, some cell clusters exhibited up to moderate cytologic atypia. Surgical findings included endometriosis, endosalpingiosis, both endometriosis and endosalpingiosis (12 patients; 31.6%), and a variety of unrelated pelvic lesions. All cases were PAX8-positive, confirming their Mullerian origin. CONCLUSIONS: Endosalpingiosis in PWs can be diagnostically challenging. Awareness of intraoperative techniques and correlation with surgical biopsy findings are necessary to avoid a misdiagnosis of malignancy.