Case 4 -

Polypoid Endometriosis Marisa R. Nucci Brigham and Women's Hospital Boston, MA

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Clinical History 39 year old woman with 10 cm bilobed solid and cystic, partially calcified pelvic mass on CT scan. At surgery, the mass only involved the omentum. Preoperative CA-125 level was 145. Diagnosis: Polypoid Endometriosis Case 4 - Figure 1 - Polypoid endometriosis in the peritoneum, seen here as tan, homogeneous, fleshy mass with cystic change. Case 4 - Figure 2 - Polypoid endometriosis. Endometrial glands of variable size are distributed in a fibrous stroma, with focally prominent vessels. Case 4 - Figure 3 - Polypoid endometriosis. A higher power view displays the the fibrotic stroma and vessels (lower right). Case 4 - Figure 4 - Polypoid endometriosis. The glands are uniform in contour and encircled by loosely arranged stromal cells. Stromal cuffing andmitoses are not present. Discussion Polypoid endometriosis is a variant of endometriosis that has a tendency to mimic a neoplasm clinically, surgically and by pathologic examination. The lesions tend to grow as polypoid masses, hence the term 'polypoid endometriosis' with only a subset of examples showing histologic features of polyps (prominent thick walled vessels, fibrous stroma, irregularly spaced and cystic glands). From a historical perspective, the term 'polypoid endometriosis' was first used by Mostoufizadeh and Scully in their description of a variant of endometriosis that shared histologic features with endometrial polyps. [1] Since their original description, there have been only a handful of case reports with the largest series on the subject recently reported by Parker et al. [2, 3, 4, 5, 6, 7, 8, 9, 10, 11] In this series of 24 women, patients' ages ranged from 23 to 78 years (median 55) with 60% of the patients being older than 50 years. A little less than half of the patients were taking exogenous hormones, possibly a contributing factor to the occurrence of endometriosis in older (peri and postmenopausal) women. Patients most commonly present with symptoms related either to a pelvic mass, vaginal mass (with associated bleeding) or large bowel obstruction. Practically any site in the abdominal cavity may be affected, with involvement of the colon, pelvic structures, vaginal mucosa, omentum and retroperitoneum having been described in descending order of frequency. On gross examination, lesions may be of varying size ranging from 0.4 to 14 cm in maximal dimension. They tend to appear as tan/brown, white/grey or pink/red polypoid masses involving mucosal or serosal surfaces or within an endometriotic cyst. Histologically, the lesions are comprised of an admixture of endometrioid glands and stroma, of which the former may show varying degrees of proliferation and metaplastic change, including tubal, mucinous, squamous and papillary syncytial metaplasia. The stroma typically resembles proliferative phase endometrial stroma without stromal cytologic atypia. In the majority of cases, stromal mitotic activity was minimal (mean mitotic index < 1). In a subset of cases, stromal fibrosis and numerous thick walled vessels are present, similar to that seen in endometrial polyps. Polypoid endometriosis is benign. In the series by Parker et al, followup in 17 (of 24) patients showed that 15 patients were alive without evidence of disease (range of followup 1 – 20 years with a mean of 5.9), one patient was alive with endometriosis at 18 months and one patient died of unrelated causes. Similar to typical endometriosis, malignant transformation may potentially occur, with epithelial, mesenchymal and mixed epithelial-mesenchymal tumors arising out of this lesion. The principal differential diagnostic consideration is the distinction of polypoid endometriosis from Mullerian adenosarcoma, particularly since the latter can arise from peritoneal endometriosis. [12] Mullerian adenosarcoma can be distinguished from polypoid endometriosis by 1 the presence of stromal papillae and frond-like proliferations that project into glandular or cystic spaces, 2) (at least mild) stromal cell atypia and 3) periglandular cellular stromal cuffing. Also within the differential diagnosis is endometrial stromal sarcoma with glandular differentiation [13], which can be distinguished from polypoid endometriosis by 1) its characteristic finger-like permeative growth pattern, 2) its propensity for lymphatic/vascular invasion and 3) usually only the focal presence of endometrioid type glands. References Mostoufizadeh M, Scully RE. Malignant tumors arising in endometriosis. Clin Obstet Gynecol 1980;23:951-63. Parker RL, Dadmanesh F, Young RH, Clement PB. Polypoid endometriosis: a clinicopathologic analysis of 24 cases and a review of the literature. Am J Surg Pathol 2004;28:285-97. Benz EJ, Dockerty MB, Dixon CF. Polypoid endometrioma of the colon: report of case in which unusual pathologic features were present. Mayo Clin Proc 1952;27:201-8. Chang A, Natarajan S. Polypoid endometriosis. Arch Pathol Lab Med 2001;125:1257. Crum CP, Wible J, Frick HC, et al. A case of extensive pelvic endometriosis terminating in endometrial sarcoma. Am J Obstet Gynecol 1981;140:718-9. Ferraro LR, Hetz H, Carter H. Malignant endometriosis; pelvic endometriosis complicated by polypoid endometrioma of the colon and endometriotic sarcoma; report of a case and review of the literature. Obstet Gynecol 1956;7:32-9. Grouls V, Berndt R. Endometrioid adenoma (polypoid endometriosis) of the omentum maius. Pathol Res Pract 1995;191:1049-52. Jimenez RE, Tiguert R, Hurley P, et al. Unilateral hydronephrosis resulting from intraluminal obstruction of the ureter by adenosquamous endometrioid carcinoma arising from disseminated endometriosis. Urology 2000;56:331. Kano H, Kanda H. Cervical endometriosis presented as a polypoid mass of portio cervix uteri. J Obstet Gynaecol 2003;23:84-5. Othman NH, Othman MS, Ismail AN, Mohammad NZ, Ismail Z. Multiple polypoid endometriosis--a rare complication following withdrawal of gonadotrophin releasing hormone (GnRH) agonist for severe endometriosis: a case report. Aust N Z J Obstet Gynaecol 1996;36:216-8. Schlesinger C, Silverberg SG. Tamoxifen-associated polyps (basalomas) arising in multiple endometriotic foci: A case report and review of the literature. Gynecol Oncol 1999;73:305-11. Yantiss RK, Clement PB, Young RH. Neoplastic and pre-neoplastic changes in gastrointestinal endometriosis: a study of 17 cases. Am J Surg Pathol 2000;24:513-24. Clement PB, Scully RE. Endometrial stromal sarcomas of the uterus with extensive endometrioid glandular differentiation: a report of three cases that caused problems in differential diagnosis. Int J Gynecol Pathol 1992;11:163-73.