Caroli's syndrome evaluated by ultrasound and magnetic resonance imaging during pregnancy

Caroli's syndrome (CS; also known as Grumbach's disease) is characterized by non-obstructive intrahepatic bile ductal ectasia and dilatation, classified as mono- or multilobar, and it is associated with congenital hepatic fibrosis1. Caroli's disease (CD) presents with similar characteristics to those of CS, but without hepatic fibrosis. Due to the similarities between CS and CD, some authors consider them to be different stages of development of the same disease2. With an estimated prevalence of 1 in 10 000 births3, CS has been reported in children, adolescents and adults. However, diagnosis during pregnancy is rare, and only a few cases have been described to date. CS is caused by a mutation in the polycystic kidney and hepatic disease 1 (PKHD1) gene on chromosome 6. Autosomal recessive polycystic kidney disease (ARPKD) is present in almost all cases of CS. We present the case of a primiparous 37-year-old woman who, following a normal ultrasound (US) examination at 13 weeks of gestation, was diagnosed at 21 weeks with enlarged and hyperechogenic fetal kidneys in association with oligohydramnios. A diagnosis of ARPKD was suggested. At 28 weeks, magnetic resonance imaging (MRI) was performed using a 1.5-Tesla scanner. The enlarged fetal kidneys and dilated biliary tree appeared hyperintense on T2-weighted sequences (Figure 1). The liver presented biliary duct dilatation with visible 'central dot' (C-DOT) sign. Based on these findings, a diagnosis of CD with ARPKD and lung hypoplasia was suggested. Follow-up US examinations were performed at 31, 33 and 35 weeks' gestation, and follow-up MRI was performed at 35 weeks and confirmed the findings of the earlier examination (Figure 2). Following preterm labor at 35 + 2 weeks' gestation, a female neonate was delivered via Cesarean section (due to breech presentation) with a length of 48 cm and weight of 2645 g. The neonate expired 55 min after delivery because of severe respiratory insufficiency due to lung hypoplasia. The autopsy confirmed the prenatal diagnosis and additionally showed liver fibrosis, establishing a definitive diagnosis of CS (Figure 3). The C-DOT sign can help differentiate CD and CS from other causes of intrahepatic biliary dilatation. It is considered to be a pathognomonic sign, caused by a portal vein branch protruding into the bile duct, and can be observed postnatally by MRI, US and computed tomography (CT), though it is not always visible4. MRI is the best imaging method to visualize the dilated biliary tree and has the highest accuracy for detecting the C-DOT sign (77.8%) as compared with CT (71.4%) and US (27.3%)5. In our case, increasing dilatation of the biliary tree during gestation indicated progressive development of CS (Figure S1). However, the late onset of signs may be related to the intensity of ductal dilatation or the limited capability of US and MRI to detect this small characteristic prenatally, which is consistent with previous reports in which the C-DOT sign was absent or not described prenatally in four out of five cases with intrahepatic bile ductal dilatation (Table S1). In conclusion, we have described the prenatal diagnosis and evaluation of CD, which should be considered in cases with ARPKD. Signs of CD may not be visible during the early stages of pregnancy, and MRI may be helpful to detect liver biliary tree dilatation. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.