The present study, to the author’s knowledge, is the first attempt to investigate the incidence of the coexistence of MCTs and endometriosis and to evaluate the differential clinical characteristics of patients with this complex condition.
Although MCTs and endometriosis are benign diseases that commonly affect women of reproductive age, the coexistence of MCTs and endometriosis, especially in a single ovary, is rare [6, 15, 16]. However, in this study, this coexistence was not rare. Although this study included a relatively small number of patients, the incidence of coexisting MCTs and endometriosis was 22.54% and its incidence in a single ovary was 7.04%. Recently, Matalliotaki et al. proposed that endometriosis is linked with an increased risk of benign gynecological tumor, such as ovarian cyst, adenomyosis and uterine leiomyomas [17]. In that study, dermoid cysts (1.5%) were observed in women with endometriosis. This data and the present study’s findings suggest that coexisting MCTs and endometriosis may be more common than previously reported.
MCTs are often discovered incidentally in asymptomatic women [1, 10]. Patients with MCTs develop symptoms such as discomfort or pain when MCTs are complicated by torsion, rupture, and infection [6]. However, various types of pain are associated with endometriosis: dysmenorrhea, deep dyspareunia, and pelvic pain unrelated to intercourse or menstruation, such as pain during defecation or urinating [18]. Sonographic examination is the initial method for identifying adnexal cystic structures, but MCTs can be occasionally difficult to distinguish from endometriomas, hemorrhagic cyst, and mucinous cystic neoplasm based on ultrasonography alone[19], and additional modalities including CT or MRI may be needed. However, the complexity and rarity of coexisting MCTs and endometriosis make it more difficult to diagnose. This study demonstrated a high prevalence of coexisting MCTs and endometriosis in those presenting with dysmenorrhea. The occurrence of dysmenorrhea was more common among women with this complex condition, whereas most MCTs occurred without clinical symptoms. The diagnosis of concomitant endometriosis in patients with MCTs rests on a high index of suspicion. Thus, gynecologic symptoms such as worsening dysmenorrhea may be a diagnostic clue.
Further, in this study, the operative time was significantly shorter in patients with MCTs alone than in patients with coexisting MCTs and endometriosis. In addition, in one patient with a histologic admixture of MCTs and endometriosis in an ovarian cyst, the procedure was converted to laparotomy because of dense adhesions and a larger ovarian cyst (exceeding 10 cm in diameter). These observations indicate that concurrent endometriosis with MCTs makes surgery much more difficult.
The recommended management of MCTs is generally surgical removal because of a large cyst size, risk of torsion, and concern for occult malignancy. Traditionally, MCTs have been removed by elective surgery and this procedure accounts for 20–35% of the surgical removal of ovarian tumors [1, 20]. MCTs are the most common germ cell tumors of the ovary in women of reproductive age, and account for approximately 70% of benign ovarian neoplasms in women under 30 years of age [21, 22]. The major concern among these younger women is future fertility. Therefore, the appropriate treatment of MCTs in children and adolescents remains unclear. A retrospective study by Hoo et al. found that the success rate of expectant management of MCTs was high and suggested that this approach be considered as a viable alternative to surgical management [1]. O’Neill et al. suggested that close follow-up without intervention should be considered to preserve ovarian function and future fertility in children and adolescents with MCTs [3]. However, endometriosis found in conjunction with MCTs makes justifying the expectant approach even more challenging. Endometriosis is a common disorder in adult women. Goldstein et al. reported a 47% prevalence of endometriosis in adolescents undergoing laparoscopy for pelvic pain [23.24]. Several studies reported a reduced number of retrieved oocytes for in vitro fertilization and premature ovarian failure after surgery for endometriosis [25.26]. The present study’s results showed that the rate of decline of serum AMH levels was significantly higher in patients with coexisting MCTs and endometriosis than in patients with MCTs alone. The study’s small sample size makes generalizing the conclusion difficult, but this result suggests that surgical cystectomy for this condition in a single ovary could cause more damage to the ovarian reserve.
The malignant transformation of MCTs is an uncommon complication, with an incidence of 0.17–2% [3, 4]. However, endometriosis is present in about 10–15% of ovarian cancers and is usually associated with endometrioid carcinoma or clear cell adenocarcinoma [27]. Moreover, Anteby et al. reported that the recurrence rate of MCTs following cystectomy was 3–4% [28]. Recurrence rates of endometrioma after surgical excision vary considerably, ranging from 6 percent through 30 percent [29.30]. Consequently, patients with coexisting MCTs and endometriosis may have an increased risk of malignancy and recurrence.
Further, a collision tumor is defined as the coexistence of two adjacent, but histologically distinct tumor components [31]. Collision tumors have been reported in various organs including the esophagus, stomach, liver, bone, kidney, central nervous system and lung, and so on, but such tumors are relatively rare in the ovary [32]. In addition, the most common histologic combination of a collision tumor in the ovary is the coexistence of teratoma and mucinous tumors; therefore a combination of teratoma with serous cystadenoma is rare [33].
This study had several limitations. First, not all patients had pathology-confirmed endometriosis. Second, the reverse case–the presence of MCTs in patients with endometriosis– was not considered. In addition, the number of patients analyzed was small.