Background

Simple hepatic cyst is a congenital biliary malformation, its origin is derived in aberrant bile ducts that have lost communication with the biliary tree and continue to secrete intraluminal fluid [1, 2]. Numerous terms have been used to designate this cystic lesion in the literature, including biliary cyst, nonparasitic hepatic cysts, benign hepatic cyst, congenital liver cyst, unilocular cyst of the liver, and solitary liver cyst [1, 3]. They occur in the general population with a prevalence of up to 5% and are increasingly diagnosed due to the increased use of imaging methods [3,4,5]. Female-to-male ratio is 1.5:1 for all simple cysts shown at imaging or necropsy, while for symptomatic or complicated simple cysts is 9:1 [2]. Localization in the right hepatic lobe is twice as frequent as the left hepatic lobe, especially in segment 5 [6]. The incidence and size of cysts increase dramatically in adults older than 50 years [1, 2, 4]. Congenital solitary nonparasitic cysts of the liver are extremely rare in the pediatric population [6]. Surgical treatment is indicated for symptoms, complications, cysts with progressive increase in size and to rule out malignancy [1]. Complete excision has the lowest recurrence rates and good long-term results [7].

We performed a systematic literature review of all cases of simple hepatic cyst in the pediatric population (0–16 years) undergoing surgical treatment (Table 1). We found 52 cases with a mean age of 2.54 years, 51% were girls and 60% were symptomatic, with abdominal distension being the most common symptom. In the 29 cases reporting liver function tests, only 2 (7%) were altered tests. As for the location, 44% were exclusively in the right lobe and 29% were exclusively in the left lobe, the remaining cases occupied both hepatic lobes. All 52 cases were treated surgically, and in 56% complete excision of the cyst was performed, 96% of cases had an uneventful postoperative course with a mean follow-up time of 21 months. Fifteen percent of the cases were pedicled cysts, 9.6% had cystobiliary communication, and only 1 case reported intracystic bleeding, detected only in the anatomopathological examination.

Table 1 Simple hepatic cyst in pediatric population (0–16 years)
Full size table

We report a case of a 13-year-old girl who was presented with a symptomatic giant solitary bile cyst with intracystic bleeding. This case is the second biggest simple hepatic cyst reported in pediatric population, the biggest pedicled cyst, and the only one with intracystic bleeding detected in pre-operative image examination in this group. Intracystic bleeding is the most common complication of simple hepatic cyst in the general population [8], but rare in the pediatric population according to our review. This case brings important considerations about this complication and its pre-operative diagnosis.

Case presentation

A 13-year-old girl, melanodermic, presented with the history of sporadic abdominal pain a few years ago, worsened in the last three months, increased abdominal volume and feeling of heaviness in the abdomen. The pain was initially mild, oppressive, located mainly in the right upper quadrant of the abdomen, without reports of anorexia, nausea, vomiting, or weight loss. At the physical exam, the patient was in good general condition, stained, hydrated, and anicteric. Cardiovascular and respiratory system examination showed no alteration. Absence of adenomegaly. Abdomen bulging in epigastric and right flank regions, presence of palpable mass, hardened and painful to deep palpation, with rounded margins and firm consistency.

Admission ultrasound (US) showed liver with normal size, regular contours, homogeneous sonic echotexture, and absence of biliary tract dilatation. Presence of expansive formation, predominantly solid with cystic areas, occupying almost the entire upper abdomen, measuring about 23 cm × 16 cm. Kidneys and spleen without alterations. Laboratory tests showed mild anemia, hemoglobin of 11.8 g/dL (normal 12–17 g/dL) and hematocrit of 36.7% (normal 36–50%). Electrolytes and liver function tests were normal. Alpha-fetoprotein and human chorionic gonadotropin were also measured and were within normal limits.

Abdominal computed tomography (CT) revealed a large abdominal expansile formation, in close relation to the lateral portion of the left liver lobe (Fig. 1A). It extends to the level of L4, dislocating the stomach, transverse colon, and small bowel loops, causing a bulging of the anterior wall of the abdomen (Fig. 1B). It had well-defined limits, encapsulated, regular contours, heterogeneous content of cystic predominance, and no evidence of calcifications or fats inside. The estimated size and volume were 25 cm × 22 cm × 12.5 cm and 3595 cm3, respectively. At magnetic resonance imaging (MRI) of the abdomen, the lesion presented predominantly high signal intensity on T2-weighted sequences, with heterogeneous hypersignal content on T1-weighted sequences, with no evidence of contrast enhancement, suggesting cystic lesion with hematic content due to intracystic bleeding. Absence of dilation of the bile ducts intra and extra-hepatic and laterally displaced gallbladder.

Fig. 1
figure 1

Computerized tomography of the abdomen. A Contrast CT, late venous phase, showing a large cystic formation, in close relation to the lateral portion of the left liver lobe, dislocating the stomach, transverse colon, and small bowel loops. B It extends to the level of L4, with well defined limits, encapsulated, regular contours and no evidence of calcifications or fats inside

Full size image

Among the diagnostic hypotheses, the possibilities of hepatic lesion with exophytic growth (mesenchymal hamartoma, with cystic predominance) and congenital cystic lesion with heterogeneous content due to probable bleeding were considered. Although the differentiation between a hepatic cyst with a blood clot and a hepatic cystic tumor is often difficult, in this case, as MRI well reflect the morphological features of a simple hepatic cyst with intracystic bleeding, they may provide the most important information for the diagnosis. In general, simple hepatic cysts are hypointense on T1 and hyperintense on T2; however, in the presence of intracystic bleeding, they are hyperintense on both T1 and T2 [9]. In addition, disagreement between US (solid predominant lesion) and CT (cystic predominant lesion) findings is also important to establish the diagnosis of a simple hepatic cyst associated with intracystic hemorrhage, because US usually visualizes the intracystic blood clot such as papillary, nodular, or irregular septal images, and CT cannot clearly visualize the intracystic hemorrhage [10].

With the probable diagnosis of symptomatic and complicated simple hepatic cyst, surgical treatment was indicated. The patient underwent a supra and infra umbilical median laparotomy, showing a large cystic lesion, linked to segments II and III of the liver by a narrow bridge of hepatic tissue, without adherence to other organs (Fig. 2A, B). Complete excision of the lesion, which weighed 3890 g, was performed.

Fig. 2
figure 2

Intraoperative images. A A pedicled cyst linked to the liver by a narrow bridge of hepatic tissue. B Final aspect of the left lobe of the liver (segments II and III) after complete excision of the lesion

Full size image

The postoperative period passed without complications, the patient discharged on the 5th day for follow-up in the outpatient clinic. The anatomopathological study revealed a cystic lesion covered by fibrotic wall, with entrapment of biliary ductal structures and hepatocyte parenchyma, containing macrophagic-like cells inside, a large amount of cytoplasm, hematic, and necrotic material. Immunohistochemistry confirmed cystic lesion with hemorrhagic areas covered by mucosecretory columnar epithelium simple without atypia. In the lesion wall, there was entrapment of hepatocytes and bile ducts, besides positivity for cytokeratin in the lining cells, suggesting the diagnosis of solitary biliary cyst.

Conclusions

Simple hepatic cyst is a rare condition in childhood. The absence of symptoms, laboratory alterations or the presence of nonspecific abdominal manifestations make this diagnosis difficult. Imaging examination are essential and histopathological analysis is decisive for diagnostic confirmation. Although intracystic bleeding is the most common complication in adults, this is not repeated in the pediatric population according to our review. Knowing how to recognize intracystic bleeding is important, because in addition to being a factor that predisposes the cyst to rupture, it also changes the appearance of the lesion on imaging tests, from a homogeneous lesion to a heterogeneous one, which can be more easily confused with malignant lesions (cystadenoma or a cystadenocarcinoma). The MRI is essential in the investigation, because, in the presence of intracystic bleeding, the images are hyperintense on T1 and T2. Comparisons between US (solid predominant lesion) and CT (cystic predominant lesion) findings associated with anemia history can improve the probability of this complication.