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Soonchunhyang Med Sci > Volume 28(2); 2022 > Article
Hong, Han, and Jeon: Polypoid Endometriosis, a Benign Tumor with Perplexing Radiologic Features: A Case Report

ABSTRACT

Polypoid endometriosis is a rare form of endometriosis. It is a benign variant but its radiologic findings trick clinicians into concern about the tumor being malignant. A 42-year-old patient with a history of dysmenorrhea and adenomyosis presented a 60 mm-sized mass in the Douglas pouch with irregular echogenicity. The patient went under the first surgery for tumor removal, and its histopathologic diagnosis was endometriosis. We started daily dienogest medication to suppress tumor recurrence, but after 10 months we decided to stop the medication due to the side effects. Four months after the cessation, a new tumor recurred and after few months of observation, we performed the second surgery of tumor removal and total hysterectomy because of adenomyosis. The tumor was located in the retroperitoneal space in the Douglas pouch with severe adhesions. After the second surgery, the tumor marker Cancer antigen-125 level was normalized and the histopathologic result was endometriosis, which we concluded as polypoid endometriosis.

INTRODUCTION

Endometriosis is a common gynecologic disease in women of reproductive age. The common sites for endometriosis are the ovaries, salpinges, vagina, cervix, rectovaginal septum, and the uterosacral ligaments [1]. The uterosacral ligaments and posterior cul-de-sac are the most common site of pelvic implantation while the gastrointestinal tract is the most common extra-pelvic site of endometriosis [2].
Polypoid endometriosis is a very rare variant of endometriosis, which was first described by Mostoufizadeh and Scully [3] in 1980. Stewart and Bharat [4] classified polypoid endometriosis into two groups: group 1 to be histologically usual endometriosis involving anatomical sites that facilitated exophytic or polypoid growth and group 2 to be endometriosis histologically resembling endometrial polyps. The radiologic finding usually shows bizarre exophytic tumors which can be easily mistaken as ovarian or peritoneal malignancy.
We report a case of a patient with a complex cystic mass in the Douglas pouch which was diagnosed as polypoid endometriosis. The tumor recurred after the cessation of dienogest so a second operation was done.

CASE REPORT

A 42-year-old married female patient, G2P2, with lower abdominal pain and left pelvic mass which was found by transvaginal ultrasonogram (TVU) was transferred to our clinic with the impression of tubo-ovarian abscess. Obstetric history was unremarkable with two normal vaginal deliveries and the patient suffered from dysmenorrhea. She previously tried a levonorgestrel-releasing intrauterine device (Mirena; Bayer, Whippany, NJ, USA) but removed it due to abnormal uterine bleeding. The TVU image at the first visit shows a 60 mm-sized heterogeneous mass with an irregular hypoechogenic area in the center of the left pelvic cavity (Fig. 1A). The abdominopelvic computed tomography (APCT) images show a lobulated low attenuation lesion with peripheral enhancing (Fig. 1B). Since she was afebrile and laboratory findings favored acute pelvic inflammatory disease than tubo-ovarian abscess, we chose not to perform emergency diagnostic laparoscopy and treated with antibiotics (cefotetan with doxycycline). After giving antibiotics treatment, symptoms improved.
Cancer antigen-125 (CA-125) level at the first visit was elevated by 219.6 IU/mL. We planned surgery and took a pelvic magnetic resonance imaging (MRI) with contrast enhancement. The T2-weighted image showed 59 mm×49 mm heterogeneous enhanced mass in the pouch of Douglas (Fig. 1C).
At the operation field of diagnostic laparoscopy, the left ovary was macroscopically normal. We noticed and resected an exophytic polypoid tumor was noticed between the left pelvic wall and large bowel, behind the uterine posterior wall (Fig. 2A, B). Since the patient strongly wanted to preserve the uterus, we decided to do the tumor resection without a hysterectomy.
A histopathologic exam concluded the tumor endometriosis (Fig. 3A, B). We prescribed dienogest 2 mg (Visanne) daily to prevent the recurrence of the disease. While taking the medication, the CA-125 level decreased to 61.5 IU/mL with no evidence of tumor recurrence on TVU. However, the patient complained about abnormal uterine bleeding and weight gain after medication, we discussed the pros and cons and decided to stop taking it after 10 months. Trying gonadotropin-releasing hormone agonists was also considered. However, we decided to make a short-term follow-up visit without any medication because there was no evidence of recurrence at the time.
The CA-125 level started to rise and 4 months after cessation of taking dienogest (which is 14 months after the surgery), a 40 mm-sized mixed echogenic mass around the left uterine adnexa was noted on TVU (Fig. 4A), and APCT image showed a complex cystic mass (41 mm×33 mm) around the area we removed the tumor in the last surgery (Fig. 4B). Another set of pelvic MRI was taken to reveal a retroperitoneal mass (54 mm×39 mm×35 mm) (Fig. 4C), so we decided to do another surgery.
A total laparoscopic hysterectomy with mass removal was planned. This time, surgical plan included a hysterectomy to eliminate other causes of the CA-125 level rise. We could notice the mass in the retroperitoneal space after adhesiolysis of advanced adhesions of the left pelvic cavity from the previous surgery (Fig. 5). The tumor was located near the left ureter, so we inserted a ureteral (Double J) stent before resecting the tumor to prevent ureteral injury.
The histopathologic test reported a uterine myoma and adenomyosis of the uterus, and the polypoid mass was endometriosis. The CA-125 level taken a month after the second surgery was normalized to 9.4 IU/mL. The patient started taking the dienogest 2 mg daily again, and there is no sign of recurrence so far. Weight gain is still an issue but the patient is trying not to gain weight with lifestyle modification.
The patient provided written informed consent for the publication of clinical details and images.

DISCUSSION

Endometriosis is an estrogen-dependent benign disease that is defined as the presence of endometrial glands and stroma outside the endometrium.
Polypoid endometriosis is a rare form of the common disease that mimics a neoplasm on clinical, surgical, and gross examination [5]. Preoperative diagnosis is difficult to make, particularly when an endometriotic MRI sign is absent. However, few recent imaging studies help us to narrow the diagnosis. According to Takeuchi et al. [6], polypoid endometriosis showed high signal intensity on T2-weighted images. Peritoneal lesions were associated with pelvic endometriosis and peripheral low-intensity rims were observed as “black rim sign” which is also noticed in this case [6].
Even though endometriosis is a benign disease, it is also a chronic disease and requires long-term management. Medical treatment to suppress recurrence should be considered to avoid repeated surgeries [7].
Several studies provide evidence that long-term dienogest use prevents recurrence and has an effect on a reduction in recurrent endometrioma size [8]. In this case, for the 10 months when the patient was taking dienogest 2 mg every day, there was no sign of recurrence. However only 4 months after stopping the medication due to weight gain and abnormal uterine bleeding, we could suspect a recurrence based on the rise of CA-125 and sonographic and APCT findings.
CA-125 has relatively low sensitivity and specificity, but it is widely used in clinical practice as a prognostic factor rather than a diagnostic marker of endometriosis [9]. The CA-125 level was lowered but not normalized after the first surgery. We decided to perform not only mass removal but also a hysterectomy because the patient also had adenomyosis which is another possible variable that can increase the CA-125 level.
Endometriosis has infiltrative nature and often invades the adjacent organs or peritoneum. Polypoid endometriosis may also show a similar invasive tendency [10]. The second surgery was more complicated than the first one since the polypoid endometriotic mass was penetrating retroperitoneal space near the ureter.
Many radiologic findings are suggested to help to make the differential diagnosis of polypoid endometriosis, but a histopathologic exam of the specimen obtained through surgery is still crucial and the only way to rule out malignancy [6].

CONFLICT OF INTEREST

No potential conflict of interest relevant to this article was reported.

Fig. 1
The imaging findings obtained by transvaginal ultrasonography (TVU) (A), abdominopelvic computed tomography (B), and magnetic resonance imaging (C). (A) TVU revealed a cystic mass, which contained fluid part with uneven echogenicity and a solid portion (white arrows), near the left adnexa. (B) Axial image showing lobulated 55 mm-sized lesion with low attenuation and peripheral enhancement in the left pelvic cavity (white dotted circle). (C) Axial T2-weighted image at the level of the anus. A lobulated, heterogeneously T2-hyperintense mass is shown in the Douglas pouch. Black rim sign is noted (white arrowheads).
sms-28-2-129f1.jpg
Fig. 2
Intraoperative image of the first surgery. (A) The tumor was found in the Douglas pouch (white dotted circle). (B) The left ovary (LO) was seen intact and separated from the tumor. UT, uterus; LS, left salpinx; LB, large bowel.
sms-28-2-129f2.jpg
Fig. 3
Hematoxylin and eosin (H&E) microscopic finding of the tumor of the Douglas pouch showed ordinary endometrial stroma and glands with focal hemorrhage. (A) (H&E, ×40). (B) (H&E, ×100).
sms-28-2-129f3.jpg
Fig. 4
The imaging findings obtained by transvaginal ultrasonography (TVU) (A), abdominopelvic computed tomography (APCT) (B), and magnetic resonance imaging (MRI) (C). (A) TVU revealed a cystic mass, which contained heterogeneous ground glass echogenicity in the left pelvic cavity (white circle). (B) APCT axial image showed 41 mm-sized ovoid cystic mass with heterogeneous enhancement abutting to uterine posterior wall in the left pelvic cavity (white dotted circle). (C) Axial T2-weighted image showed a mass with complex attenuation located in the retroperitoneal space of the left pelvic wall (white arrowheads).
sms-28-2-129f4.jpg
Fig. 5
Intraoperative image of the second surgery. The tumor was found in the Douglas pouch in the retroperitoneal space (white dotted irregular circle). UT, uterus; IP, left iliopsoas muscle.
sms-28-2-129f5.jpg

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