Macrophages in human fallopian tube and ovarian epithelial inclusion cysts

Epithelial inclusion cysts (EICs) are considered a preferential site for ovarian carcinogenesis. Local inflammation, associated to ovulatory wound repair and epithelial inflammatory conditions, facilitates EIC formation and involves activation of macrophages. The aim of this study was to analyse the presence and numbers of macrophages in the ovarian surface epithelium (OSE), in EICs, and in the fallopian tubes, as tubal metaplasia is a common finding in EICs. Immunohistochemical analysis of macrophages was performed in 25 fallopian tubes in different phases of the menstrual cycle, and in 30 ovaries showing EICs from cycling and postmenopausal women. In the fallopian tube, macrophages were abundant and underwent cyclic changes during the menstrual cycle, being particularly abundant within the epithelium at early and mid-luteal phases. Macrophages were not found in the normal OSE. However, OSE areas and EICs showing tubal metaplasia were invariably associated with infiltration by abundant macrophages. Macrophages were present among epithelial cells, infiltrating the cyst wall, as well as free in the cyst lumen. No significant differences existed between follicular and luteal phases of the cycle, or between cycling and postmenopausal women. This study has demonstrated that macrophages are associated with metaplastic EICs, and raises the possibility that these cells contribute to the particular microenvironment of EICs through secretion of cytokines and growth factors that may reach bioactive concentrations in the confined space of the EICs.