Omental endosalpingiosis with endometrial-type stroma in a woman with extensive hemorrhagic pelvic endometriosis.

A 38-year-old woman with extensive hemorrhagic endometriosis causing back pain, pelvic masses, and hydronephrosis also had a palpable omental mass composed of abundant endometrial-type stroma in which the epithelial component was entirely tubal type glandular cells; the stroma in this area did not bleed. This difference in bleeding behavior supports the concept that patterns of differentiation of heterotopic müllerian tissues may depend in part on the influence of local factors and that endometrial epithelium may produce a local trophic or paracrine factor that is absent in tubal epithelium.