Extrapelvic "Uterus Like Mass" Following Laparoscopic Morcellation Hysterectomy-a Consequence of Iatrogenic Implantation?

Uterus-like mass (ULM) is a rare form of endometriosis, which shows striking structural similarity to the normal uterus. Formation of a mass lesion raises clinical concern for malignancy, and pathologic examination is necessary for accurate diagnosis. We describe herein, a middle aged woman who presented with a mesenteric mass six years post hysterectomy, which was initially suspected to be a gastrointestinal stromal tumor. The resected was specimen was grossly pear shaped with microscopy showing a central endometrial glands and stroma lined cavity, surrounded by a thick muscular wall reminiscent of uterine myometrium. Histogenesis of this entity is unclear, and several theories are proposed regarding the etiology, including congenital anomaly theory, metaplasia and heterotopia theories. Our clinical scenario developed a few years after uterine morcellation, indicating a possibility of another "iatrogenic implantation" theory behind the pathogenesis of this rare lesion.