Ultrasound Findings in Endosalpingiosis: A Closer Look at an Overlooked Condition.

Endosalpingiosis is a rare, benign condition characterized by ectopic cystic glands lined with ciliated cuboidal epithelium, histologically resembling the fallopian tube. Its etiology remains uncertain but is hypothesized to result from either ectopic implantation of fallopian tube tissue or metaplastic transformation of multipotential peritoneal cells. While frequently misdiagnosed as endometriosis, endosalpingiosis coexists with endometriosis in ~35% to 40% of cases. The condition can affect both women of reproductive age and postmenopausal individuals, with a median age of diagnosis between 50 and 52 years. While often asymptomatic, patients may present with infertility, pelvic pain (including dysmenorrhea and dyspareunia), pelvic masses, or urinary symptoms such as hematuria or dysuria when lesions involve the urinary bladder. Lesions primarily localize to the peritoneal surfaces of the uterus, fallopian tubes, ovaries, and cul-de-sac but can rarely extend to the bladder, ureters, bowel serosa, omentum, lymph nodes, appendix, cervix, and even the skin. Endosalpingiosis is considered part of the spectrum of peritoneal serous lesions and may be associated with or progress to borderline or low-grade ovarian serous neoplasms. Sonographic evaluation typically reveals multiple small, anechoic, and avascular cystic structures forming a "bunch-of-grapes" pattern along pelvic and peritoneal surfaces.