**1. Introduction**

52 Endometriosis - Basic Concepts and Current Research Trends

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#### **1.1 Introduction and epidemiology**

Endometriosis is the extrauterine occurrence of endometrial glands and stroma, most often involving the ovaries or dependent visceral peritoneal surfaces. This tissue responds to the hormone variations in the cycle similar to eutopic endometrium.

Endometriosis is most commonly a disease of women in the second half of their reproductive life, between 30 and 45 years, and tends to regress at the menopause or even before. As a significant gynecological problem, endometriosis occurs in 7%–10% of the general population and up to 50% of premenopausal women (Wheeler, 1989). It is found in 20%–50% (mean 38%) of infertile women (Rawson, 1991; Strathy, 1982; Verkauf, 1987), and in 71%–87% of those with chronic pelvic pain (Carter, 1994; Koninckx et al., 1991; Ling, 1999). Endometriosis is responsible for 20% of all gynecologic operations and is the single leading nonobstetric cause (.5%) of hospitalization for women age 15–44 years. Although benign, endometriosis is progressive, tends to recur, may be locally invasive, may have widespread disseminated foci (rare), and may exist in pelvic lymph nodes (30%) (Martin & Pernoll, 2001).

Endometriosis is commonest in the pelvis. It is very occasionally found in bizarre sites such as the pleura, umbilicus, Caesarean section scars, perineam or vagina, diaphragm, arm, leg or kidney, but these cases are rare. The following statistical data shows the order of frequency: ovaries (30%), uterosacral and large ligaments (18–24%), fallopian tubes (20%), pelvic peritoneum, pouch of Douglas and gastrointestinal tract. Extraperitoneal locations include cervix (0.5%), vagina and rectovaginal septum, round ligament and inguinal hernia sac (0.3–0.6%), navel (1%), abdominal scars after gynecological surgery (1.5%) and cesarean section (0.5%). Endometriosis rarely affects extra-abdominal organs such as the lungs, urinary system, skin and central nervous system (Bergqvist, 1993; Lin et al., 2006).

Perineal endometriosis (PEM) is the presence of endometrial tissues in the perineal sites. It has been published in obstetric and gynecologic literature since 1949. A retrospective study in Peking Union Medical College Hospital shows 17263 women received surgical treatment for endometriosis between Jan 1992 and Apr 2011. Of them, 64 women (3.7‰) were with PEM. Of these 64 women, cases of PEM with anal sphincter involvement were 31 (1.8‰). That is, in nearly half of women with PEM, the lesions erode into anal sphincter.

Diagnosis and Treatment of Perineal Endometriosis 55

Ideyi et al., 2003). From an etiologic perspective, the present case can be explained with postoperative menstrual implantation within the open perineal wound resulting from the procedure. Another mechanism of transplantation would see silent foci of unknown, asymptomatic pelvic endometriosis that could have been present at the time of surgery and have been disseminated within the wound edges. These foci developed into overt disease

There is a growing awareness of risk of possible transformation of endometriosis into an invasive malignancy. This is rare but well documented, and theoretically, it can occur in any gonadal or extragonadal site of endometriosis. Since 1925, more than 200 cases of malignant transformation of endometrioma have been reported in the literature (English). Heaps et al. found that 79% of such cases occurred in the ovary, the reminder occurring in extragonadal sites, usually in rectovaginal septum, pelvic peritoneum, colon, rectum, and vagina. The 5 year survival rate in patients with localized disease treated with surgery and postoperative radiation is about 80% (Heaps et al., 1990). Malignant transformation of extraovarian endometriosis is uncommon and only 60 cases have been reported world widely until 1990;

Johana Castillo Bustamante et al. reported a 41 year-old female patient with an episiotomy in her delivery and a myomectomy performed at 31 year-old. She had symptoms for a year like progressive pain and tumour at the perineum and glutei area and cyclic bleeding. The core biopsy reported endometrioid carcinoma of perineum. She was diagnosed of "1. Pelvic tumour: Hematometra or ovarian tumour; 2. Solid tumour of right isquiorrectal area: endometroid carcinoma". When laparotomy was performed, the uterus was absent, a left ovarian endometrioma cyst and a right follicular cyst were detected, and appendix had endometrial tissues. Six months after the surgery the patient had liver metastases and she

Almost all patients with PEM are of reproductive ages and has a history of vaginal delivery. The perineal mass is often found in the episiotomy site or laceration site after vaginal delivery. Most patients have perineal cyclic pain corresponding to menstrual periods. Usually there is a mass between left labium majora and labium minora close to the clitoris. Perineal mass can be big and tender. Mostly the color of mass is normal. Sometimes the

We analyzed 36 patients with perineal endometriosis who were operated on between 1983 and 2007 at Peking Union Medical College Hospital (PUMCH) retrospectively. The mean age of the 36 patients was 30.7 years (range, 23-44 years). Mean gravidity was 2.05 (range, 1- 6) and mean parity was 1.03 (range 1-2). The median latent period (time from delivery to the women having perineal pain or nodule) of these 36 cases was between 4 months and 13 years after delivery. All cases had cyclical perineal pain, which was progressive and

color of perineum is blue. Some patients have cyclic bleeding in perineal mass.

correlated with their menstrual cycles (Zhu et al, 2009).

of them, ninety percent are endometroid carcinomas (Johana et al., 2007).

several years after surgery (Nicola et al., 2011).

**3. Malignant transformation** 

died 2 months later (Johana et al., 2007).

**4. Clinical findings and diagnosis** 

**4.1 Clinical features** 
