Endometrioid Carcinoma Of Douglas Pouch 9 Years After Vaginal Hysterectomy And Bilateral Salpingo-Oophorectomy: Is Endometriosis The Answer?

PROBLEM STATEMENTPrimary extrauterine endometrioid carcinoma arises from ectopic endometrioid tissue. In 1925, Sampson first reported malignant transformation of endometriosis to carcinoma, which may occur in up to 1% of the affected women. The ovary is by far the most common site and extragonadal malignant transformation of endometriosis has been identified in only 20% of these patients. This indicates a not negligible risk of extrauterine endometrioid carcinoma diagnosis even after hysterectomy and bilateral salpingo-oophorectomy.METHODSCase report, clinicopathologic description and overview discussion of differential diagnosis and clinical management approach.RESULTSWe report a case of a 69-year-old woman who underwent vaginal hysterectomy and bilateral salpingo-oophorectomy with Kelly-Kennedy surgery for the treatment of uterine prolapse and urinary stress incontinence. Histologic examination showed an atrophic endometrium and adnexa, with no evidence of malignancy. Nine years after the surgery, the patient presented with abnormal vaginal bleeding. Abdominopelvic CT scan showed a cystic lesion just above Douglas pouch. A vaginal cuff fistula was observed and a curettage of its tract was performed, whose biopsy pointed to endometriosis/infected cyst. Pelvic MRI revealed a 22mm diverticular nodule contiguous to Douglas pouch. Rectosigmoidoscopy had no relevant findings. Diagnostic laparoscopy was performed and a non-capsulated 3cm nodule of Douglas pouch was excised. The vaginal cuff fistula, which communicated with the mass, was vaginally repaired. Histologic examination of the surgical specimen revealed a well-differentiated endometrioid carcinoma, supported by immunohistochemical study (positive staining for cytokeratin 7 and the estrogen receptor and negative for cytokeratin 20), probably arising from foci of endometriosis considering the previous medical history. PET scan had no signs of metastatic disease. The patient completed pelvic radiotherapy and is currently completing the second year of follow-up with no evidence of relapse.CONCLUSIONIn this case, histology and immunohistochemical staining suggest endometrioid carcinoma in a woman with no uterus and adnexa. Differential diagnosis between primary endometrioid carcinoma of pelvic peritoneum, endometrioid ovarian cancer of a possible remaining ovarian stump or late metastasis of a non-diagnosed endometrioid carcinoma of the excised uterus is mandatory for clinical management and treatment approach. The fact that endometriosis was identified at the vaginal cuff fistula biopsy, the absence of other malignant peritoneal lesions and normal histologic findings in the first surgery are in favour of the diagnosis of a malignant transformation of an endometrioid lesion. Further studies should focus on the pathophysiologic mechanisms of progression to malignancy in order to identify patients with higher risk and to search for effective diagnostic tools and therapies.