Postoperative granulomas of the endometrium: histological features after endometrial ablation

Postoperative granulomas of the male urogenital tract are a well-recognized phenomenon. Similar granulomas have also been described in the uterine cervix, fallopian tube, and other sites after various procedures, as well as in the endometrium after endometrial ablation procedures. Endometrial ablation is a procedure increasingly used by gynecologists to relieve symptoms associated with dysfunctional uterine bleeding. Occasionally, patients will not have a satisfactory result, and some will require subsequent hysterectomy. We describe the pathological findings in the hysterectomy specimens from 15 patients who had previously undergone endometrial ablation. Indications for subsequent hysterectomy included dysmenorrhea (7 patients), menorrhagia (7 patients), dysfunctional uterine bleeding (5 patients), and pelvic pain (4 patients). All patients had varying degrees of fibrosis of the endometrial cavity, with some endometrial cavities completely obliterated by fibrous tissue. Histological examination revealed fibrosis with varying degrees of granulomatous inflammation. The majority of the granulomas were associated with refractile brown hematoidin-like pigment, and most were also associated with uniform black pigment. In 8 cases, areas of faintly eosinophilic, homogenous, hyalinized material were present within the endometrium. Comparison is made to granulomas due to other causes, because the postoperative granulomas of the endometrium differ morphologically from granulomatous inflammation caused by other etiologies. As endometrial ablation gains popularity among gynecologists and their patients, it is likely that the practicing pathologist may encounter these sequelae with increasing frequency.