Biliary cystadenoma masquerading as an adnexal cyst in pregnancy

Abstract

The aetiological diagnosis of cystic masses detected on routine ultrasound during pregnancy can be challenging. Unless approached cautiously with a detailed history and adequate use of imaging techniques, misdiagnosis of these cystic masses are not uncommon. Cystic masses diagnosed during pregnancy are mostly of ovarian origin; however, other non-ovarian cystic masses are also detected incidentally or at laparotomy/laparoscopy. We report a rare case of ruptured biliary cystadenoma in a pregnant woman diagnosed at emergency laparotomy. She was taken up for surgery with a provisional impression of ruptured adnexal cyst. However, the cyst was found to be arising from the liver and the histology of the cyst wall was reported as biliary cystadenoma.

Background

The increasing use of prenatal ultrasound has led to detection of a large number of adnexal masses in pregnancy.¹ They are most often asymptomatic and identification during pregnancy causes a lot of apprehension and anxiety for both patients and their care providers. The lack of established guidelines to the approach and management of incidentally detected cystic masses in pregnancy makes the matter even more challenging.² These masses can be functional cysts, neoplastic (benign or malignant) or inflammatory masses. Occasionally, they can be non-gynaecological in origin. Ultrasound, though useful, has its limitations for the evaluation of large cystic masses in pregnancy. MRI gives better characterisation as it has increased soft tissue resolution and also helps in differentiating between benign and malignant masses in 93% of the cases.³

Management of incidentally detected cystic masses in pregnancy is controversial, with some opting for surgical intervention in the second trimester and others resorting to observation. The rationale for conservative management is based on the fact that most cysts regress spontaneously either during or after pregnancy and surgical intervention carries an increased risk of preterm labour and fetal compromise. However, during observation, some can undergo torsion or rupture mandating emergency surgical measures. An elective surgical intervention for these masses during pregnancy is based on the size, site and nature of the mass.⁴ Though the majority of these cysts are ovarian in origin, some non-ovarian cysts are diagnosed incidentally on imaging or at laparotomy. The benign ovarian cysts reported are usually corpus luteal cysts, haemorrhagic cysts, dermoid cysts, theca lutein cysts, serous or mucinous cystadenomas of the ovary or hyperstimulated ovaries. Other cystic masses that are non-gynaecological include omental cysts, mesenteric cysts, mucocoele of the appendix, biliary cystadenoma and peritoneal inclusion cysts.

Biliary cystadenoma (BCA) and cystadenocarcinoma (BCAC) comprise less than 5% of all liver cysts. Hepatobiliary cystadenomas occur most frequently in middle aged women and spontaneous rupture of these are extremely rare.⁵ They are often misdiagnosed and inadequate treatment leads to recurrence of the tumour. Here we present a case of ruptured BCA in a pregnant woman. The intraoperative findings, follow-up and successful management of both pregnancy and cystadenoma are presented below.

Case presentation

A 30-year-old woman, G2A1 with history of secondary infertility of 9 years and conception following intrauterine insemination presented to our emergency department at 26 weeks gestational age with multiple episodes of vomiting, generalised abdominal pain and difficulty in breathing of 1 day duration. She had her previous antenatal visits at a local hospital where she was detected to have a right adnexal cyst during routine morphology scan. The cyst was anechoic and measured 15×18 cm with multiple thin septations. A therapeutic aspiration of the cyst was done at the same hospital where clear fluid was drained. She presented to us a month later with the above complaints.

On arrival, she was found to be tachycardic (pulse rate 124/min) and tachypneic (Respiratory rate -32/min, SpO2 98% room air) with a blood pressure of 90/60 mm Hg. Abdomen was distended with generalised tenderness and guarding. The uterus was found to be pushed to the left side and fetal heart sounds were heard. An emergency bedside ultrasound revealed a large anechoic adnexal cyst on the right side, measuring 13×14×12.6 cm with multiple thick septations and gross free fluid. A provisional diagnosis of rupture of the cyst was made and she was taken up for emergency laparotomy. Intraoperatively, uterus was 26 weeks and adnexae were found to be normal. There was nearly a litre of purulent ascites with flakes of pus over the duodenum and hepatic flexure of colon. Surgeons were called in and a thick walled cyst with clear non-bile stained fluid was noted to be arising from the under surface of the central segments of the liver (figure 1). Peritoneal lavage with decompression of cyst, biopsy of cyst wall and primary closure of cyst was done. Surgical resection of the cyst was not attempted as the cyst would have to be mobilised from the liver, the extent and pathological nature of the cyst was unclear and prolonged surgery would increase the risk of preterm labour. Following surgery, she was administered intravenous meropenem for 2 days which was changed to piperacillin-tazobactam for a total duration of 5 days. The antibiotic was downgraded after the blood and peritoneal fluid cultures sent were reported as sterile. She had an otherwise, uneventful postoperative recovery.

Figure 1.

Intraoperative picture showing cyst arising from the under surface of the liver.

Investigations

Serum tumour markers done showed elevated CA 19–9 levels (483 U/mL) and normal CEA and CA-125 levels. Total leucocyte count was normal with neutrophil predominance (12,100/mm³). Histopathological examination of the cyst wall revealed features consistent with biliary cystadenoma (cyst wall contained ovarian like stroma) and cyst fluid analysis showed elevated CA 19–9 levels (>20 000 U/mL). Peritoneal fluid and cyst fluid cytology showed features of inflammation with no evidence of malignancy. MRI done postoperatively reported the presence of a large well-defined cystic lesion with thick septations and few T2 intermediate solid components arising from segment 8/4A of the liver with a large exophytic component extending inferiorly with mass effect and mild biliary dilatation (figure 2).

Figure 2.

MRI showing large well-defined cystic lesion with thick septations arising from segment 8/4A of the liver.

Differential diagnosis

The diagnosis considered at the time of presentation was ruptured adnexal/ovarian cyst as the scans done elsewhere had suggested an adnexal cyst and she also had a history of cyst aspiration in early pregnancy. With acute features on presentation and a large cyst in the right adnexa with gross ascites on bed side imaging, she was taken up for an emergency laparotomy. Intraoperatively, the cyst was found to be arising from the undersurface of the liver. Cyst wall analysis and MRI confirmed biliary cystadenoma.

Treatment

A multidisciplinary team meeting was held by the treating obstetric unit with the hepatobiliary surgeons and neonatologists and a decision to electively deliver her at 34 weeks was taken as hepatobiliary cystadenomas are reported to increase in size during pregnancy secondary to the hormonal effect and, therefore, are at a greater risk of rupture. An elective resection of the hepatic cyst would be planned in the postpartum period after the baby was weaned off breastfeeding.

She was on regular follow-up and serial liver function tests done were normal. She was readmitted at 32 weeks with complaints of increasing abdominal discomfort and fullness. Steroids were administered for fetal lung maturation and she was managed as in-patient thereafter. A week later, she was taken up for emergency caesarean section for suspected rupture of the cyst and a 1.9 kg preterm baby boy was delivered. Intraoperatively, there was no evidence of rupture of the cyst and definitive surgery for the biliary cystadenoma was deferred till 6 months post partum as previously planned. Postoperatively, she was monitored for a week and discharged.

Outcome and follow-up

She was later followed up by the hepatobiliary team and a repeat MRI, 4 months later showed an increase in cyst size (17–21 cm) with compression of the main bile ducts in the hilum (figure 3). There was an increase in intrahepatic biliary radicle dilatation (IHBRD) on the left lobe. She did not have clinical jaundice and liver function tests repeated were normal. Indocyanine green (ICG) clearance test done showed ICG R15=5.2% and plasma disappearance rate of 19.7% per minute. In view of significant pressure effect and distorted biliary anatomy, she underwent elective endoscopic stenting of the right and left hepatic ducts followed by excision of the cyst with segment four duct margin and cholecystectomy. Histopathological examination of the same was reported as biliary cystadenoma with low grade dysplasia and mild cholecystitis.

Figure 3.

MRI showing large well-defined cystic lesion with increase in size to 14×21×22 cm as compared with previous image.

Discussion

Hepatobiliary cystadenomas are rare, cystic, slow growing tumours that can arise from any portion of the biliary tree though the majority of them have an intrahepatic predilection.⁶ The exact aetiology of these cysts is not known. The theories suggested with regards to its origin includes it arising from remnants of the primitive foregut concealed in the liver, secondary to obstruction of an abnormal bile duct, as a response to repeated local injury to the biliary tract and a probable hormonal role as a large number of these cysts are diagnosed in middle-aged women around the age of 50.^{7 8} They are most often detected incidentally and are asymptomatic. Symptoms caused by these cysts are usually related to the mass and pressure effects—mainly increasing abdominal distension, feeling of fullness, early satiety, nausea and occasionally pain.⁹ They can also present with jaundice secondary to biliary obstruction, haemorrhage into the cyst and rupture of the cyst. Diagnosis of these cysts in the asymptomatic can therefore be challenging.

Imaging plays a big role and aids in differentiating from simple cysts, parasitic cysts, hydatid cysts and haemorrhagic cysts. Ultrasound helps in detection of septations and mural nodules whereas MRI helps in identifying the depth of extension into liver and also involvement of biliary tree and hepatic vessels. The nature of the cyst whether serous, mucinous or haemorrhagic is usually based on the varying signal intensity obtained on MRI.¹⁰ The tumour markers are most often normal, though CA 19–9 and CEA can be elevated in the cyst fluid.¹¹

Hepatobiliary cystadenomas are classified based on their epithelial lining with the mucinous type being more common as compared with their serous counterpart. The mucinous cystadenomas are further typed based on the presence or absence of mesenchymal ovarian stroma in between its epithelial lining.¹² Cystadenomas with mesenchymal stroma have a predilection for females and is considered premalignant with a favourable outcome whereas the ones without mesenchymal stroma is not gender specific. The latter carries a worse prognosis because of increased tendency for malignant transformation which is often associated with dissemination. The biliary cystadenomas with ovarian stroma are hormone responsive and hence tend to increase in size during pregnancy thereby increasing chances of rupture. Spontaneous rupture of these biliary cystadenomas is rare with only few cases reported in literature. Definitive management of these cystadenomas require complete excision, sometimes involving partial or total lobectomy of the involved liver as it has a tendency to recur and can also undergo malignant change.¹³ Radical surgery is therefore mandatory and follow-up of cases reported have shown good outcomes both in the short and long term.

Though most of the biliary cystadenomas occur in middle aged women and are incidentally diagnosed as a multiloculated cystic mass, ours presented in a 30-year-old pregnant woman with features of acute abdomen mimicking a ruptured adnexal cyst. Detailed evaluation following the initial surgery, a multidisciplinary approach, close monitoring of the patient and the decision to deliver at a gestational age without jeopardising the fetus or increasing the risk of spontaneous rupture a second time helped in achieving a successful outcome.

Learning points.

• Cystic masses of non-gynaecological origin can complicate pregnancy. Acute abdomen in pregnancy can present in a variety of ways and identification of cause requires a detailed algorithmic approach.

• To be aware that ultrasound has limitations in the evaluation of large cystic masses and the additional use of MRI is most often mandatory.

• Large and complex adnexal masses often need a multidisciplinary approach. The indication for surgery in pregnancy, its appropriateness, timing and mode requires counselling in detail so as to achieve a favourable outcome for both the mother and baby.

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