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Ectopic production of HCG by a benign ovarian mature cystic teratoma simulating an extra-uterine pregnancy: a case report.

Introduction

The incidence of an ectopic pregnancy is one in fifty pregnancies in the United States; however, pregnancy in a woman post tubal ligation is more likely to be an ectopic pregnancy compared to the general population. One third of post-sterilization failures are ectopic pregnancies due to the disruption of normal tubal anatomy. (1) Pregnancy following a tubal ligation by the Pomeroy method is as high as 16%; pregnancy can occur because of spontaneous re-anastomosis of the Fallopian tubes or fistula formation.

An ectopic pregnancy mimics a normal intrauterine pregnancy until significant hemorrhage occurs. Breast tenderness, nausea, frequent urination, and amenorrhea are common symptoms of both intra-and extra-uterine pregnancies. Fifty percent of women with an ectopic pregnancy are asymptomatic until a fallopian tube ruptures. (2) They may present with vaginal bleeding, abdominal cramping and pain. A tubal rupture may result in severe internal bleeding which can lead to shock and death. Ectopic pregnancies may resolve by spontaneous tubal abortion expelling the pregnancy without complications, but frequently, pain, bleeding, and hemorrhagic shock are associated. Ectopic pregnancies must be identified and removed early to avoid these life-threatening complications.

Transvaginal ultrasound can detect an intrauterine pregnancy with a Beta-hCG level of 1500 mIU/ ml and detect an extra-uterine pregnancy in up to 80 percent of women. An ectopic pregnancy is treated with either medical management such as Methotrexate or surgical management such as laparoscopy. Afterwards, HCG concentrations are monitored weekly until levels drop below 5 mIU/mL.

Trophoblastic tissue secretes beta-hCG and the differential diagnosis for an elevated serum HCG concentration includes intra-uterine and extra-uterine pregnancy, gestational trophoblastic neoplasia, and ovarian germ cell tumors. Forty percent of complete moles are associated with an HCG concentration greater than 100,000 mIU/mL. (3) Sequellae of a molar pregnancy can be persistent gestational trophoblastic neoplasia (GTN) or choriocarcinoma. An abnormally large uterus, advanced maternal age, and abnormally elevated HCG levels raise suspicions for malignant GTN. Metastasis to the lung, liver, bone, etc. most often occurs from a choriocarcinoma within the ovary. Choriocarinomas develop from extra-embryonic differentiation of malignant germ cells of the placenta as opposed to molar pregnancies which are benign trophoblastic cells generated from abnormal fertilization. Ultrasound may reveal the abnormality, but histological examination is necessary to confirm the diagnosis.

Serum pregnancy markers such as alpha-fetoprotein (AFP) and HCG are useful when diagnosing a particular ovarian germ cell tumor. Granulosa cell tumors elevate inhibin levels while embryonal carcinomas increase AFP and HCG. The most common ovarian tumor is the mature cystic teratoma (dermoid cyst) which is usually hormonally inactive. Ultrasound is used to make a diagnosis and ovarian cystectomy is used to confirm the diagnosis, preserve ovarian tissue, and allow for removal.

Case Report

A 31-year old gravida 2 para 0-2-0-2 complained of amenorrhea, abdominal discomfort, nausea, and breast tenderness and had a positive home pregnancy test. She had a Pomeroy tubal ligation three years ago and a known right dermoid cyst. An office quantitative beta--HCG was 41,428 mIU/mL. A transvaginal ultrasound was performed and did not find an intrauterine pregnancy. An ectopic pregnancy was considered the most likely cause of her positive HCG.

The patient's past medical history consisted of chronic abdominal pain and chronic hypertension. She had undergone two cesarean deliveries due to preterm severe preeclampsia and had a pomeroy tubal ligation with her second. Three days post partum; she developed a low grade fever and underwent computed tomogram of the abdomen revealing a 6x10 cm right dermoid cyst. She was asymptomatic and was discharged but did not follow-up with gynecology until this admission. She had been evaluated by surgery for her chronic abdominal pain and had a second abdominal computed tomogram scan in 2008 revealing the 6 x 10 cm midline dermoid lesion, nonobstructing right nephrolithiasis, and cholelithiasis. She underwent a laparoscopic cholecystectomy in 2008. Other prior surgeries included a total thryroidectomy for hyperthyroidism. She was currently on thyroid replacement and an antidepressant. Her family history was remarkable for diabetes and hypertension. She did not desire future childbearing. Once she discovered the positive home pregnancy test, she went to the emergency room for evaluation. The transvaginal ultrasound or emergency room pelvic exam did not demonstrate an ovarian mass and the previous computed tomogram scan report was unavailable.

The plan was a diagnostic laparoscopy with possible oopherectomy or salpingectomy to identify and remove the presumed ectopic pregnancy. Laparoscopic findings included a modestly enlarged anteverted uterus with a large right ovary containing an 11 x 9 x 4.5 cm cyst. The left ovary appeared normal and both fallopian tubes displayed prior tubal ligation and did not demonstrate a tubal pregnancy. She underwent a laparoscopic right salpingo-oopherectomy and endometrial curettage. The specimen required a minilaparotomy for removal. Pathology reported that the 11 cm grey-tan specimen was a benign mature cystic teratoma. Sectioning of the cyst found caseous material, hair, and partially calcified areas. The endometrial pathology was also evaluated and demonstrated a benign hypersecretory endometrium without atypia. There was no evidence of chorionic villi on either specimen.,

Following the operation, the patient's HCG concentration was halved to 25,427 mIU/mL and was monitored weekly. One week postoperatively, her HCG was reported at 12,953 mIU/mL; three weeks post-operatively her HCG was 35.4 mIU/mL; and four weeks it was 5.9 mIU/mL. The patient continued to have her HCG levels monitored for two more negative results.

Discussion

The differential diagnosis for elevated human chorionic gonadotropin levels is pregnancy, gestational trophoblastic neoplasia (GTN), and ovarian tumors. This patient's presenting symptoms were suspicious for an extra-uterine pregnancy following tubal ligation. However, the negative pelvic ultrasound and endometrial curretage made GTN and ectopic pregnancy unlikely.

Dermoid cysts or mature cystic teratomas are usually an inactive, benign combination of all three embryonic germ cell layers, containing sebaceous fluid, hair, and even teeth. Common in the second and third decades, these cysts may present with symptoms depending on their size and susceptibility for torsion. Approximately one percent of dermoid cysts contain malignant cells that develop into squamous cell carcinoma later in life and the patient's extremely high HCG level warranted serious concern. Choriocarcinoma was a possible source of her elevated HCG but the negative endometrial curettage with decreasing HCG levels was reassuring.

This patient's dermoid cyst was particularly unusual for several reasons. It was missed at the time of her repeat cesarean section and again at the time of her cholecystectomy. The higher fat content of a larger dermoid cyst typically provides easier visualization on CT scan; conversely, its greater buoyancy may make the ovary high in the peritoneal cavity and not palpable by pelvic exam. She had undergone two prior surgeries and the large dermoid cyst was not visualized. In the case of her cesarean section, the ovary was pushed high in the upper abdomen by the gravid uterus and was missed by the operating surgeon. During her cholecystectomy, she was placed in reverse Trendelenburg resulting in the dermoid cyst returning to a pelvic location and was missed by the general surgeon. Second, the cyst's reported size in 2007 was large, but it continued to grow in the subsequent three years. On average, a dermoid cyst grows 1.8 mm each year. (5)

Finally, this cyst appeared to have secreted significant amounts of HCG and rather suddenly since the patient never complained of amenorrhea or pregnancy-like symptoms in the past two years. This benign dermoid's HCG production simulating an ectopic pregnancy resembles two similar published cases. (5,6) Downey et. al. published the first case in London in 1989 and very few cases have been reported since then. (7) (See Table 1 for a comparison between this case's cyst and a previously reported cyst.) Laparoscopic removal of the dermoid resulted in an immediate decrease in HCG concentration further suggesting ectopic HCG production by the cyst. Furthermore, cyst removal eliminated the patient's abdominal discomfort, pregnancy-like symptoms, and risk of torsion.

The origin of the high HCG levels could not be confirmed; pathology was unable to perform HCG staining on the preserved specimen. The lack of a gestational sac or chorionic villi within the specimen made an ectopic pregnancy or GTN unlikely. Because the patient's HCG concentrations immediately decreased upon removal of the right ovary, the dermoid most likely produced the extremely high HCG levels.

Fortunately, the patient's symptoms have resolved and the dramatic decrease in her serum HCG concentration was reassuring. Because the oopherectomy and pathology reported a benign cystic teratoma that coincided with normalization of HCG levels, it was presumed that a rare occurrence of an HCG secreting dermoid cyst was the source of production of her high beta-hCG levels that mimicked an ectopic pregnancy. This case demonstrates the need to perform a thorough exam of intra-abdominal structures during scheduled surgical procedures to avoid missing significant pathology resulting in an additional future surgical procedure for treatment.

References

(1.) Current Trends Ectopic Pregnancy--U.S., 1990-1992. Morbidity and Mortality Weekly Report 1995;44:46.

(2.) Buckley RG, King KJ, Disney JD, Gorman JD. History and physical examination to estimate the risk of ectopic pregnancy: validation of a clinical prediction model. Ann.Emer. Med. 1999;34:589.

(3.) Berkowitz RS, Goldstein DP. Chorionic tumors. NEJM 1996;335:1740.

(4.) Ayhan A, Bukulmez O, Genc C. Mature cystic teratomas of the ovary: case series from one institution over 34 years. Eur J Obstet Gynecol Reprod Biol 2000;88:153.

(5.) Caspi B, Appelman Z, Rabinerson D. The growth pattern of ovarian dermoid cysts: a prospective study in premenopausal and postmenopausal women. Fertility and Sterility 1997;68:501.

(6.) Pothula V, Matseoane S, Godfrey H. Gonadotropin-producing benign cystic teratoma simulating a ruptured ectopic pregnancy. JAMA 1994;86:221.

(7.) Downey GP, Prentice M, Penna LK, Gleeson RP. Ectopic beta-human chorionic gonadotropin production by a dermoid cyst. Amer J of Ob and Gyn 1989;160:449.

(8.) The risk of pregnancy after tubal sterilization. Findings from the U.S. Collaborative Review of Sterilization, Peterson HB, Xia Z., Hughes JM, Wilcox LS, et al, Am J Obstet Gynecol 1996 Apr;174(4):1161-8.

Brenda Dawley, MD

Associate Professor Department Ob/Gyn

Andreia Acuna, MD

OB/Gyn Resident

Beatrice Grasu, MD

Joan C. Edwards School of Medicine, Huntington
Table 1: Dermoid cyst comparison between a previously published case
and this case

Dermoid Cyst   Dawley 2010          Pothula 1994

Patient        31-year old   24-year old
Size           11x9x4.5 cm   14x8x6 cm
HCG Level      41,428 HCG    Positive, unreported value
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Title Annotation:Scientific Article
Author:Dawley, Brenda; Acuna, Andreia; Grasu, Beatrice
Publication:West Virginia Medical Journal
Article Type:Clinical report
Geographic Code:1USA
Date:Jan 1, 2012
Words:1737
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