A small organ takes center stage: selected topics in fallopian tube pathology.

In this paper we consider a number of non-neoplastic and neoplastic lesions of the fallopian tube. Emphasis has been placed on diagnostically difficult entities, some of which result in misdiagnosis and consequent alteration of treatment, including "pseudocarcinomas" that represent a florid epithelial response to acute and/or chronic salpingitis. Endometriosis-related lesions may cause infertility, or undergo malignant transformation to a Mullerian carcinoma, most frequently endometrioid and clear cell types. Pregnancy-related tubal lesions include the easily misdiagnosed metaplastic papillary tumor as well as several manifestations of ectopic pregnancy. Covered briefly are familial conditions such as the Peutz-Jeghers syndrome and its association with tubal mucinous metaplasia, clear cell papillary cystadenoma associated with von Hippel-Lindau syndrome, and the Li Fraumeni syndrome's germline p53 mutation and its association with distal tubal p53 signatures. Miscellaneous tumors discussed include the common adenomatoid tumor and the uncommon female adnexal tumor of probable Wolffian origin. Important issues including the updated staging of fallopian tube carcinomas, and the histopathologic variants of endometrioid carcinomas and their sometimes unusual patterns that engender the potential for confusion with other tumors are briefly noted. The final section covers the relatively recent and novel concept of the fallopian tube as the predominant site of origin of ovarian and peritoneal carcinomas. Discussed are the histologic, immunohistochemical, and molecular biologic evidence that support the tubal fimbria as the site of serous tubal intraepithelial carcinoma, possibly the immediate precursor to high-grade ovarian and peritoneal serous carcinoma.