CASE REPORT A subserosal uterus-like mass presenting after a sliding hernia of the ovary and endometriosis: a rare entity with a discussion of the histogenesis Atsuko Seki, M.D., a Arafumi Maeshima, M.D., a Hiroyuki Nakagawa, M.D., b Junichi Shiraishi, M.D., a Yuya Murata, M.D., a Hiroharu Arai, M.D., b Kiyoshi Kubochi, M.D., c and Shigeru Kuramochi, M.D. a a The Pathology Division, Clinical Laboratories, and b Department of Obstetrics and Gynecology, National Hospital Organization Tokyo Medical Center, Tokyo; and c Department of Surgery, National Hospital Organization Tokyo Medical Center, Tokyo, Japan Objective: To report the first case of a subserosal uterus-like mass. Design: Case report. Setting: A community-based hospital. Patient(s): A 44-year-old nulliparous woman who complained of a left inguinal mass had a medical history that was notable for two features. One was left oophorectomy for a sliding hernia at 10 months of age; the other was endometriosis at the oophorectomy site at 26 years of age. Intervention(s): Tumorectomy. Main Outcome Measure(s): Not applicable. Result(s): Pathologic examination demonstrated that this subserosal mass mimicked a miniature uterus with a leiomyomatous lesion. Conclusion(s): As of September 2010, 23 cases of uterus-like mass had been reported. Three pathologic theories of uterus-like mass have been proposed: [1] congenital anomaly theory, [2] metaplasia theory, and [3] heterotopia. The pathogenesis of this rare entity is currently under debate. Most uterus-like masses have been connected to the genital (75.0%) and associated with endometriosis (50.0%). In the present case, the uterus-like mass developed at the surgical scar site of oophorectomy for a sliding hernia and a tumorectomy for endometriosis. We review the literature and discuss the theories regarding the histogenesis of uterus-like mass. (Fertil Steril Ò 2011;95:1788.e15 e19. Ó2011 by American Society for Reproductive Medicine.) Key Words: Uterus-like mass, endometriosis, metaplasia theory, histogenesis, subserosal tissue Uterus-like mass is a rare entity first described by Cozzutto in 1981 (1). It represents a tumorous lesion composed of endometrial tissue and smooth muscle, histologically resembling the uterus. Although the histogenesis has been controversial, to date 24 cases have been reported including our case (1 18). Most uterus-like masses have arisen in the pelvic cavity. There have not been any previously reported cases of uterus-like mass arising in the inguinal subserosal region. We describe the first case of a subserosal uterus-like mass. CASE REPORT Our case is a 44-year-old nulliparous woman who displayed a mass in a left inguinal surgical scar that became larger and more painful Received October 3, 2010; revised November 17, 2010; accepted November 22, 2010; published online December 23, 2010. A.S. has nothing to disclose. A.M. has nothing to disclose. H.N. has nothing to disclose. J.S. has nothing to disclose. Y.M. has nothing to disclose. H.A. has nothing to disclose. K.K. has nothing to disclose. S.K. has nothing to disclose. Reprint requests: Atsuko Seki, M.D., The Pathology Division, Clinical Laboratories, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro-ku, Tokyo, 152-8902 Japan (E-mail: aseki@ntmc.hosp.go.jp). during her menstrual period. She had two characteristic features in her medical history. One was a sliding hernia of the left ovary at 10 months of age. She had undergone herniorrhaphy and left oophorectomy. The other was endometriosis in the surgical scar in the left inguinal region at 26 years of age. Pathologic information from the first operation was not available. Review of slides of the second surgical specimen showed endometriosis. Transvaginal ultrasound scanning showed that her uterus had a normal size and the right ovary was normal. Magnetic resonance imaging examination of the pelvis demonstrated a highly enhanced mass in the left inguinal subserosal tissue, measuring 3.8 2.0 cm (Fig. 1). There were no congenital anomalies. Tumorectomy was performed. During the procedure, an elastic, hard tumor was found in the subfascial space. The tumor was not mobile from the surrounding tissue. The cordlike accessory structures adhered to the peritoneum. Surgically, the resected tumor was located between the fascia and the peritoneum. MATERIALS AND METHODS The surgical specimen was fixed in 10% formalin, and paraffinembedded sections were stained with hematoxylin and eosin 1788.e15 Fertility and Sterility â Vol. 95, No. 5, April 2011 0015-0282/$36.00 Copyright ª2011 American Society for Reproductive Medicine, Published by Elsevier Inc. doi:10.1016/j.fertnstert.2010.11.051
FIGURE 1 Magnetic resonance imaging scan of the pelvis with IV gadolinium enhancement, demonstrating an enhanced mass in the left inguinal subserosal tissue (white arrow). (H&E). Immunohistochemical staining of paraffin sections was performed with use of a standard antigen technique. We investigated the immunohistochemical examination using antibodies against CD10, estrogen receptor (ER), progesterone receptor (PR), smooth muscle actin (SMA), and desmin. RESULTS The mass measured 4 cm in diameter, and the yellowish-white cut surface demonstrated areas with small holes and a nodular leiomyomatous area. Microscopic examination demonstrated that the holes were lined by the mid proliferative phase endometrium surrounded by a thick layer of smooth muscle (Fig. 2). The examination demonstrated that the small nodule was indeed a leiomyomatous lesion. In the cordlike structure, endometriosis and collagenous fiber were seen. Immunohistochemically, the glandular cells in the endometrial tissue were positive for ER and PR, and the stromal cells in the endometrial tissue were positive for CD10. The smooth muscle cells surrounding the endometrial tissue were positive for PR, in addition to SMA and desmin. These histologic findings closely resembled uterine structures. DISCUSSION Twenty-three cases of a uterus-like mass had been reported as of September 2010 (1 18). A total of 24 cases including the present case are summarized in Table 1. All patients presented with a mass resembling the uterus. The most frequent locations were female genital (n ¼ 18): ovaries (41.7%), uterus (25.0%), and broad ligament (12.5%). Other locations in the abdominal cavity were ileum (n ¼ 1) and mesentery (n ¼ 1). This is the first case of a uterus-like mass arising in the inguinal subserosal region. In all cases, the uterus-like mass measured from 2 to 14 cm (mean 6.3 cm). Various congenital anomalies were in six patients (2, 3, 14, 16, 17). Twelve cases (50.0%) were associated with endometriosis (1, 4, 6, 9, 11 13, 16, 17). There are three chief theories regarding the pathogenesis of uterus-like mass: [1] congenital anomaly theory, [2] metaplasia theory, and [3] heterotopia. A congenital malformation has been suggested in five cases because there were associated malformations (2, 3, 14, 16). Cozzutto (1) first reported a uterus-like mass and postulated that the uterus-like mass originated from a transition from ovarian stromal cells to smooth muscle fibers through the stage of myofibroblast, supported by ultrastructural findings. Since then, 16 case reports proposed that the uterus-like mass originated from metaplasia (1, 4, 6 13, 17, 18). In most cases, malformation could not be found (1, 4, 6 13, 16 18). These studies suggested that smooth muscle developed through the metaplastic transformation of ovarian stromal cells, endometrial stromal cells, or subcoelomic tissue. Heterotopia was proposed as the cause of the uterus-like mass of the conus, and an embryologic origin of ectopic m ullerian tissue associated with spinal dysraphism was suspected (18). Uterus-like mass is an extremely rare disorder; however, endometriosis is a common disorder found in almost 10% of women of reproductive age (19). Jenkins et al. (20) studied by laparoscopy the anatomic distribution of ectopic endometrium in 182 consecutive patients with infertility caused by endometriosis. Frequent sites were uterus (11.5%), right ovary (31.3%), and left ovary (44.0%). The distribution of endometriosis is similar to that of the uteruslike mass. It is of interest that the rate of endometriosis among cases of uterus-like mass is much higher than the prevalence of endometriosis in the general population. Both endometriosis and uteruslike mass show a similar anatomic distribution. In the present case, the uterus-like mass developed at a surgical scar site in which endometriosis had been demonstrated previously on histologic examination, and cordlike tissue with endometriosis was attached to the uterus-like mass. Because of these findings, we postulate that endometriosis plays some role in the pathogenesis of uterus-like mass. Furthermore, we favor the metaplasia theory in the present case of uterus-like mass. However, it remains unknown why metaplastic transformation occurs, and the cause of metaplasia in our case could not be determined. In summary, this is the first reported case of a subserosal uteruslike mass. The pathogenesis of uterus-like mass remains controversial, but we assume that metaplasia is most likely in our case. Fertility and Sterility â 1788.e16
FIGURE 2 (A D) Subserosal uterus-like mass. (A) Subserosal uterus-like mass showing a lumen lined by endometrial mucosa (white arrow), surrounded by smooth muscle layer including a leiomyomatous nodule (black arrow) (H&E, original magnification 1). (B, C) Endometrial mucosa in the mid proliferative phase comprising glands and stromal cells was seen in the left field. Bundles of smooth muscle cells were seen in the right field (H&E, original magnification 20, 200). (D) Leiomyomatous nodule was composed of smooth muscle bundles (H&E, original magnification 20). 1788.e17 Seki et al. Subserosal uterus-like mass Vol. 95, No. 5, April 2011
Fertility and Sterility â 1788.e18 TABLE 1 Reported cases of uterus-like mass. Reference no Age (y a ) Endometriosis b Anomaly Size (cm) Intra-abdominal Female genital Location Nongenital Extra-abdominal Speculated histogenesis 1 31 þ N.D. 6 Ovary 2 18 þ þ 4 Ovary Anomaly 3 12 N.D. þ 2.5 Ileum Anomaly 4 38 þ N.D. 5 Ovary 5 18 N.D. N.D. 2.5 Conus Heterotopia 6 49 þ N.D. 8 Ovary 7 46 N.D. 16 Broad ligament 8 34 N.D. 2 Ovary 9 39 þ N.D. 13 Ovary 9 43 N.D. N.D. 11.5 Ovary 9 38 N.D. N.D. 4 Ovary 10 59 N.D. N.D. 14 Mesentery 11 47 þ N.D. 2.5 Uterus 12 43 þ N.D. 3 Uterus 12 52 þ N.D. 8 Uterus 13 50 þ N.D. 5 Uterus 14 11 N.D. þ 4.5 Ovary Anomaly 15 37 N.D. 6 Uterus and broad ligament N.D. 16 33 þ 3 Conus Anomaly 16 24 N.D. þ N.D. Conus Anomaly 17 39 þ þ 7 Uterus 17 57 þ N.D. 10.5 Oophorectomized site 18 17 4 Broad ligament Present case 44 þ 4 Subserosal tissue Note: N.D. ¼ not described; þ¼reported as present; ¼reported as absent. a Age of patient. b History or complication of endometriosis.
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