Intestinal Endometriosis: Clinicopathologic Analysis of 15 Cases Including a Case of Endometrioid Adenocarcinoma

:Since many patients with intestinal endometriosis present with gastrointestinal symptoms without a history of endometriosis, endoscopic examination of the intestinal tract is initially performed, often leading to a misdiagnosis. Methods :We reviewed the clinicopatho- logic findings of 18 samples from 15 patients with intestinal endometriosis who underwent endo- scopic biopsy and/or surgical resection to identify diagnostically helpful findings. Results :All 7 biopsy specimens displayed relatively well-defined submucosal lesions, with non-mucinous glands lined by ciliated epithelium and surrounding cellular stroma containing spiral arteriole- like blood vessels. The stroma was immunopositive for CD10 in all cases. All but one speci- men exhibited immunopositivity for ER and PR in both glandular and stromal components. In contrast to the overlying normal colonic mucosa, glandular epithelium with endometriosis was immunopositive for cytokeratin (CK) 7, but immunonegative for CK20 in all cases. Three cases were associated with adenocarcinoma in the same or different segments; specifically, two primary rectal adenocarcinomas and one endometrioid adenocarcinoma arising from endometrio- sis. Conclusions :The characteristic features of endometrial glands and stroma, including non- mucinous glands without goblet cells, ciliated columnar epithelium, and cellular stroma with spiral arterioles, facilitate the accurate diagnosis of intestinal endometriosis, which can be con- firmed by immunohistochemical staining. Key Words : Endometriosis; Intestine; Endometrioid adenocarcinoma Heejin Lee Kyu-Rae Kim 120 Intestinal Endometriosis: Clinicopathologic Analysis of 15 Cases Including a Case of Endometrioid Adenocarcinoma 120 120 Corresponding Author Kyu-Rae Kim, M.D. Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, 388-1 Pungnap-dong, Songpa-gu, Seoul 138-736, Korea Tel: 02-3010-4514 Fax: 02-472-7898 E-mail: [email protected] Department of Pathology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea Received : July 4, 2008 Accepted : December 16, 2008 Endometriosis is defined as the growth of endometrial glands or stroma outside the uterine cavity.1 Intestinal endometriosis is relatively uncommon, occurring in 5% of women with endom- etriosis, 1,2 and the involved sites include the rectum, sigmoid, appendix, terminal ileum, and cecum, in descending order of frequency. 3 Patients usually experience abdominal or rectal pain, tenesmus, constipation, diarrhea, loose stools, and hematochezia, depending on the site involved. 1,2 Because many patients pre- sent with gastrointestinal symptoms, radiologic examination or endoscopy of the intestinal tract is usually performed at the ini- tial presentation, 4 often leading to misdiagnoses as various inflam- matory lesions or tumors of the intestine based on the findings of obstructive or infiltrative masses.2,5,6 We therefore sought to identify the pathologic characteristics of intestinal endometrio- sis by assessing the histopathologic and immunohistochemical properties of endoscopic biopsy and resected specimens. Since diagnosis of intestinal endometriosis in the resected specimens is rarely a problem, we particularly focused on endoscopic biop- sy specimens.

The surgical pathology files of the Department of Pathology, Asan Medical Center (Seoul, Korea), contained 18 verified sam- ples of intestinal endometriosis from 15 patients between 1996 and 2006. Among these patients, 4 had been diagnosed with intestinal endometriosis based on endoscopic biopsy alone, one had surgical resection after repeated endoscopic biopsies (case 5), and 10 underwent surgical resection only (cases 1-4 and 6-11). The gross and microscopic findings and the patients’clinical re- cords were reviewed in all cases. In 17 samples, immunohistochemical staining was performed on formalin-fixed and paraffin-embedded tissue sections using an autostainer (Ventana Medical Systems Inc., Tucson, AZ, USA). The primary antibodies used were cytokeratin (CK) 7 (1:200 dilution; DAKO, Glostrup, Denmark), CK20 (1:200 dilution; DAKO), CD10 (1:50 dilution; NOVO, Newcastle, UK), estro- gen receptor (ER, 1:400 dilution; NeoMarkers, Fremont, CA, USA), and progesterone receptor (PR, 1:400 dilution; NeoMark- Intestinal Endometriosis 121 ers).After incubation with the primary antibodies, immunode- tection was performed with biotinylated anti-mouse immuno- globulin followed by peroxidase-labeled streptavidin, using the LSAB kit (DAKO) and 3,3 ′-diaminobenzidine chromogen as the substrate. An endogenous biotin blocking kit was used to reduce non-specific immunopositivity (Ventana Medical Systems Inc.). Diaminobenzidine was used as a chromogen, and tissues were counterstained with hematoxylin.

Clinical findings The median patient age at the time of diagnosis was 41 years (Table 1). The presenting clinical symptoms included abdomi- nal pain (8/15 [53.3%]), hematochezia (6/15 [40.0%]), tenesmus (2/15 [13.3%]), and constipation (2/15 [13.3%]). Two patients (cases 4 and 10) exhibited no clinical symptoms, but intestinal endometriosis was incidentally detected during surgery for a vil- lotubular adenoma and an infertility work-up, respectively. Based on radiologic and clinical findings, 5 patients (33.3%) were diag- nosed with colon cancer, 5 patients (33.3%) with ovarian cysts, 3 patients (20%) with submucosal tumors of the large intestine, 1 patient (6.7%) with invasion of ovarian cancer, and 1 patient (6.7%) with appendicitis. Endometriosis was located in the rec- tum in 8 (53.3%) patients, the appendix in 6 patients (40.0%), and the sigmoid colon in 1 patient (6.7%). In 8 patients (53.3%), intestinal endometriosis was associated with histologically-proven ovarian endometriosis, and 1 patient (6.7%) with adenomyosis, while the remaining 6 patients had no history of endometriosis. TAH, total abdominal hysterectomy; BSO, bilateral salpingo-oophorectomy; LAR, low anterior resection; RSO, right salpingo-oophorectomy, LOC, left ovarian cystectomy; BOC, bilateral ovarian cystectomy; LSO, left salpingo-oophorectomy; ROC, right ovarian cystectomy; P, perirectal soft tissue; S, serosa; M, proper muscle layer; Sm, submucosa; NT, not tested. Case Age Symptoms Clinical Associated Procedure Location Involved ER/PR/CD10/ No. impression endometriosis layers CK7/CK20 1 50 Constipation Colon cancer Ovarian TAH, BSO, Appendix S, M +/+/+/+/ - endometriosis Appendectomy, Segmentectomy 2 43 Abdominal pain, Colon cancer - LAR, Rectum P +/+/+/+/ - Tenesmus, Appendectomy Hematochezia 3 53 Constipation, Colon cancer Ovarian LAR Rectum P, M +/+/+/+/ - Hematochezia endometriosis 4 42 None Colon cancer - LAR Rectum P +/+/+/+/ - 5 36 Tenesmus, Submucosal - Biopsy (x2), LAR, Rectum P, M, Sm +/+/+/+/ - Dyspareunia tumor TAH 6 42 Abdominal pain Appendicitis - Appendectomy Appendix S, M +/+/+/+/ - 7 36 Abdominal pain Ovary cyst Ovarian RSO, LOC, endometriosis Appendectomy Appendix S, M NT 8 39 Abdominal pain Ovary cyst Ovarian BOC, Appendix S, M +/+/+/+/ - endometriosis Appendectomy 9 31 Abdominal pain Ovary cyst Ovarian LOC, Appendix S, M +/+/+/+/ - endometriosis Appendectomy 10 35 None Ovary cyst Ovarian LSO,ROC, Appendix S, M +/+/+/+/ - endometriosis Appendectomy 11 41 Abdominal pain, Ovary cyst Ovarian LSO, Sigmoid S, M, Sm +/+/+/+/ - Hematochezia endometriosis Appendectomy, Segmentectomy 12 41 Abdominal pain, Submucosal Adenomysosis Biopsy Rectum Sm -/-/+/+/- Hematochezia tumor 13 45 Hematochezia Colon cancer - Biopsy Rectum Sm +/+/+/+/ - 14 47 Hematochezia Invasion Ovarian Biopsy Rectum Sm +/+/+/+/ - ovary cancer endometriosis 15 38 Abdominal pain Submucosal - Biopsy (x2) Rectum Sm +/+/+/+/ - tumor Table 1.Clinicopathological and immunohistochemical findings in patients with intestinal endometriosis 122 Heejin Lee Kyu-Rae Kim Pathologic findings Endoscopic biopsy specimens Among the 4 patients diagnosed using endoscopic biopsy alone, 1 was clinically suspected to have colon cancer, 2 with submu- cosal tumors, and 1 with colonic invasion of ovarian cancer. Seven endoscopic biopsy specimens were obtained from 5 patients (cases 5, 12-15). Each specimen contained 2-5 pieces (average, 3.5) of colonoscopic-biopsied mucosa. Endometriotic foci were relative- ly well-delineated from the surrounding normal intestinal mucosa (Fig. 1A). All 7 biopsy specimens were characterized by non-muci- nousglandular structures lined by ciliated columnar epithelium and surrounded by cellular stroma containing abundant thin- walled vasculature (Fig. 1B). Glands were irregular and larger in shape and size compared to the adjacent colonic mucosa, and lined by tall columnar epithelium cells with elongated nuclei showing regular vertical orientation. Goblet cells were absent, in contrast to the adjacent normal colonic mucosa. The epithe- lium displayed immunopositivity for CK7 (Fig. 2A), but imm- unonegativity for CK20 (Fig. 2B), in contrast to overlying nor- mal colonic mucosa, which was negative for CK7 and positive for CK20. In all samples, periglandular stroma was distinguished from the lamina propria of normal colonic mucosa by the pres- ence of short, spindle-shaped cells with inconspicuous cytoplasm and abundant small vasculature. The stroma was immunoposi- tive for CD10 in the endometriotic foci, but negative in the lam- ina propria of the colon (Fig. 2C). All but one case (case 12) sh- owed diffuse immunopositivity for ER in the endometrial glands and stroma (Fig. 2D), but endometriosis was confirmed in an ER- and PR-negative case (case 12) based on the strong imm- unopositivity for CD10 in the stroma. Surgically-resected specimens Among the 11 surgically-resected cases, the pre-operative diag- noses were as follows: colon cancer in 4 patients, submucosal tu- mors (such as a gastrointestinal tumor) in 1 patient, acute appen- dicitis in 1 patient, and ovarian cysts in 5 patients. Grossly, all 11 specimens had multifocal hemorrhagic spots on the serosal surfaces. Apart from 4 cases with adenocarcinomas or villotubu- lar adenomas, the overlying mucosa of the resected specimens remained intact. Two patients (18.2%) displayed serosal surface involvement only, 7 patients (63.6%) showed involvement of the serosa and muscle layers, and 2 patients (18.2%) had involve- ment of the serosa to the submucosa. In cases 5 and 11, the intesti- nal walls were irregularly thickened and fibrotic. Moreover, in case 5, focal cystic changes containing gray-brown material were identified in the thickened wall. Endometriosis specimens associated with adenocarcinoma Intestinal endometriosis was associated with adenocarcinoma in the same segment in 2 patients (cases 2 and 3) and in differ- ent segments in 1 patient (case 1). In cases 2 and 3, lesions of endometriosis and adenocarcinoma involved different layers of the same segment, and 1 patient (case 3) contained an endometri- oid adenocarcinoma arising from endometriosis in the same seg- ment involving the entire thickness of the rectal wall from the mucosa to the perirectal soft tissue. Clinical and pathological findings of the latter closely mim- icked those of primary colorectal cancer, with ulceration of the overlying mucosa (Fig. 3A, B), and the neoplastic glands focal- Fig. 1. Endoscopic biopsy specimen showing rectal endometriosis. (A) Endometriotic focus in the submucosa (arrows) is relatively well delineated from the surrounding normal colonic mucosa. (B) Non-mucinous ciliated epithelium and cellular stroma containing spiral arte- riole-like blood vessels are characteristic findings. A B Intestinal Endometriosis 123 ly contained mucinous epithelium (Fig. 3C). However, the mass grew into the cystic space of endometriosis lined by endometri- otic glands and stroma. The epicenter of the tumor was located in the deep muscle layer and perirectal soft tissue with only a small mucosal opening (Fig. 3A, B). In contrast to primary col- orectal adenocarcinoma and overlying normal rectal mucosa, endometrioid adenocarcinoma was strongly immunopositive for ER (Fig. 3D) and CK7 (Fig. 3E), but negative for CK20.

Clinically, intestinal endometriosis can simulate irritable bowel syndrome, acute appendicitis, inflammatory bowel disease, diver- ticulitis, submucosal tumors, or intestinal carcinoma. 7,8 While intestinal endometriosis is frequently associated with pelvic en- dometriosis, 9 gastrointestinal symptoms may be the first mani- festation of the disease.3 In our series, 4 patients (cases 5, 6, 13, and 15) presented with intestinal symptoms, such as abdominal pain, tenesmus, and hematochezia, with no history of endometrio- sis. Therefore, intestinal endometriosis should be considered dur- ing the differential diagnosis of intestinal lesions. 4,10,11While intesti- nal endometriosis occurs more frequently in women of reproduc- tive age, this factor is not critical since disease onset in 2 of our patients occurred after 50 years of age, and one had surgical me- nopause 10 years before presentation. Adenocarcinoma can arise in endometriosis, albeit rarely. 4,6,10-12 The histopathologic criteria for the diagnosis of primary adeno- carcinoma arising in endometriosis include the following: 1) clear evidence of endometriosis within close proximity to the tumor, 2) no other primary site of adenocarcinoma, and 3) his- tologic appearance similar to native endometrium of the uterus. Adenocarcinoma in endometriosis is easily confused with prima- ry colorectal carcinoma since tumor cells often contain mucin- Fig. 2.Immunohistochemical findings in intestinal endometriosis. Endometrial glands are immunopositive for cytokeratin 7 (A) and negative for cytokeratin 20 (B), in contrast to the surrounding normal colonic epithelium. (C) Dense periglandular stroma shows strong immunoposi- tivity for CD10 antibody. (D) Glandular epithelium and/or stroma are immunopositive for ER, in contrast to the surrounding colonic mucosa. A B C D 124 Heejin Lee Kyu-Rae Kim secreting epithelium. However, the growth patterns are usually different, as in our case.4 The epicenter of the tumor is usually outside the intestinal wall, but these tumors ultimately invade the intestinal wall. Compared with primary colorectal carcino- ma, the extent of mucosal involvement or the mucosal opening is generally smaller (Fig. 3A). Differentiation between adeno- carcinoma arising in endometriosis and primary colorectal carci- noma is crucial owing to better prognosis of the former and dis- tinct treatment plans. 13 In conclusion, characteristic features of endometrial glands and stroma, including non-mucinous glands without goblet cells, cili- atedcolumnar epithelium, and cellular stroma with spiral arte- rioles, are helpful in the diagnosis of intestinal endometriosis, which can be confirmed by immunohistochemical staining for Fig. 3.Endometrioid adenocarcinoma arising in rectal endometriosis. (A, B) Gross and microscopic findings of the cut surface of the tumor show its epicenter located in the deep muscle layer and perirectal soft tissue with a narrow mucosal opening. (C) Adenocarcinoma focal- ly contains mucinous epithelium (arrows), which mimics primary colonic adenocarcinoma. (D, E) Tumor cells are strongly immunopositive for ER (D) and CK7 (E). A B C E D Intestinal Endometriosis 125 CK7, CK20, ER, PR, and CD10.14-19

1. Robboy JR, Anderson MC, Russell P. Endometriosis. In: Robboy JR, Anderson MC, Russell P, eds. Pathology of the female reproductive tract. London: Churchill Livingstone, 2002; 445-70. 2. Kanthimathinathan V, Elakkary E, Bleibel W, Kuwajerwala N, Con- jeevaram S, Tootla F. Endometrioma of the large bowel. Dig Dis Sci 2007; 52: 767-9. 3. Clement PB. Diseases of the peritoneum. In: Kurman RJ, ed. Blaus- tein’s pathology of the female genital tract. 5th ed. New York: Sp- ringer-Verlag, 2002; 761-2. 4. Hoang CD, Boettcher AK, Jessurun J, Pambuccian SE, Bullard KM. An unusual rectosigmoid mass: endometrioid adenocarcinoma aris- ing in colonic endometriosis: case report and literature review. Am Surg 2005; 71: 694-7. 5. Varras M, Kostopanagiotou E, Katis K, Farantos C, Angelidou-Mani- ka Z, Antoniou S. Endometriosis causing extensive intestinal obstruc- tionsimulating carcinoma of the sigmoid colon: a case report and review of the literature. Eur J Gynaecol Oncol 2002; 23: 353-7. 6. 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. 7. Remorgida V, Ferrero S, Fulcheri E, Ragni N, Martin DC. Bowel endometriosis: presentation, diagnosis, and treatment. Obstet Gynecol Surv 2007; 62: 461-70. 8. Yantiss RK, Clement PB, Young RH. Endometriosis of the intestinal tract: a study of 44 cases of a disease that may cause diverse challenges in clinical and pathologic evaluation. Am J Surg Pathol 2001; 25: 445- 54. 9. Redwine DB. Ovarian endometriosis: a marker for more extensive pelvic and intestinal disease. Fertil Steril 1999; 72: 310-5. 10. Jones KD, Owen E, Berresford A, Sutton C. Endometrial adenocar- cinoma arising from endometriosis of the rectosigmoid colon. Gynecol Oncol 2002; 86: 220-2. 11. Petersen VC, Underwood JC, Wells M, Shepherd NA. Primary en- dometrioid adenocarcinoma of the large intestine arising in colorec- tal endometriosis. Histopathology 2002; 40: 171-6. 12. Slavin RE, Krum R, van Dinh T. Endometriosis-associated intestinal tumors: a clinical and pathological study of 6 cases with a review of the literature. Hum Pathol 2000; 31: 456-63. 13. Clement PB. The pathology of endometriosis: a survey of the many faces of a common disease emphasizing diagnostic pitfalls and unusu- al and newly appreciated aspects. Adv Anat Pathol 2007; 14: 241-60. 14. Sumathi VP, McCluggage WG. CD10 is useful in demonstrating endometrial stroma at ectopic sites and in confirming a diagnosis of endometriosis. J Clin Pathol 2002; 55: 391-2. 15. Groisman GM, Meir A. CD10 is helpful in detecting occult or incon- spicuous endometrial stromal cells in cases of presumptive endo- metriosis. Arch Pathol Lab Med 2003; 127: 1003-6. 16. McCluggage WG, Oliva E, Herrington CS, McBride H, Young RH. CD10 and calretinin staining of endocervical glandular lesions, endo- cervical stroma and endometrioid adenocarcinomas of the uterine corpus: CD10 positivity is characteristic of, but not specific for, me- sonephric lesions and is not specific for endometrial stroma. Histo- pathology 2003; 43: 144-50. 17. Fujishita A, Nakane PK, Koji T, et al.Expression of estrogen and pro- gesterone receptors in endometrium and peritoneal endometriosis: an immunohistochemical and in situ hybridization study. Fertil Ster- il 1997; 67: 856-64. 18. Bergqvist A, Ferno M. Estrogen and progesterone receptors in en- dometriotic tissue and endometrium: comparison according to local- izationand recurrence. Fertil Steril 1993; 60: 63-8. 19. Loy TS, Calaluce RD, Keeney GL. Cytokeratin immunostaining in differentiating primary ovarian carcinoma from metastatic colonic adenocarcinoma. Mod Pathol 1996; 9: 1040-4.