Papillary syncytial metaplasia of fallopian tube endometriosis: a potential pitfall in the diagnosis of serous tubal intraepithelial carcinoma.

Histopathologic diagnosis of tubal intraepithelial carcinoma (TIC) has emerged as a significant challenge in the last few years. The avoidance of pitfalls in the diagnosis of TIC is crucial if a better understanding of its natural history and outcome is to be achieved. Herein, we present a case of a 52-year-old woman who underwent a risk-reducing salpingo-oophorectomy procedure. Histologic examination of a fallopian tube demonstrated a focus of atypical epithelial proliferation, which was initially considered to be a TIC. Complete study of the case indicated that the focus was, in fact, papillary syncytial metaplasia of tubal mucosal endometriosis. Papillary syncytial metaplasia may resemble TIC and should be considered in cases of proliferative lesions of the tubal epithelium.