With the improvement of the abdominal radiological technique, more liver cystic lesions were discovered during these years. However, most majorities of cysts are HSC which is a benign disease and often no harmful to the body. IBC and IBAC are rare liver cystic tumours that were redefined as H-MCNs by WHO 2010 with the presence of an ovarian-like stoma (OS), occupying only 5% of liver cystic lesions.[3, 6, 7] H-MCNs are much more aggressive than HSC. BAC tends to transform into IBAC at about 20%. Meanwhile, it can lead to cholangitis, intestinal obstruction, peritonitis after rupturing, or other complex complications.[12–14] Thus,the treatment between HSC and H-MCNs is extremely diverse, and the accurate diagnosis of H-MCNs and HSC is of great significance. However, for the lack of specific biochemical markers and imaging features, the diagnosis of H-MCNs was still challenging. To improving the differential diagnosis between H-MCNs and HSC, some researchers make their effects on finding some statistical differences on markers. [8, 11, 15, 16]. Due to a relatively rare quantity of H-MCNs, these small-sample studies can hardly find significant features to differentiate these two lesions. Labib et at. found that H-MCNs often combined with single cyst; Koffron et at. found that cystic fluid CA19-9 and CEA level are useful in differentiating H-MCNs and HSC; while Choi et at. reported that cystic analysis of CA19-9 and CEA have no help to diagnose H-MCNs. Up to now, the imaging examination is the most effective method to diagnose H-MCNs, although there is no reliably specific radiographic feature.  In a word, the data on the diagnostic feature of H-MCNs remains scarce, and few studies about IBC and IBAC were based on the new classification of H-MCNs with the requirement of a present of OS.[3–5, 7, 9, 17, 18]
In our study, a total of 29 H-MCNs with the presence of OS were included to analyze. Major of H-MCNs occurred in women (20/29, 69%), particularly younger age women (≤ 60 year,79%), which is consistent with the previous study.[8, 15] However, there were no significant differences in age and sex between H-MCNS and HSC, indicated that sex and age were not useful to distinguish these two diseases. Some patients of H-MCNs would complain about abdominal pain (14/29, 48.3%), fever (4/29,13.8%), jaundice (2/29,6.9%) and other symptoms, the symptom of fever was significantly higher than that of HSC, which could be explained that the H-MCNs originate from some congenitally aberrant bile ducts and could lead to cholangitis.[18, 19] The presence of bile duct dilation in imaging also supported this viewpoint.
There are many studies compared the tumour markers between HSC and H-MCNs.[8, 15, 16, 20] Choi et at. found that serum tumour marker of CA19-9 was elevated in the H-MCNs but not reached a significant difference from HSC. In our study, when adjusted cut-off value to 20 U/ml, serum CA19-9 was a nearly independent factor to predict H-MCNs. Other tumour markers like CEA, CA12-5, AFP were not able to differentiate these two diseases, which are consistent with previous researches. Cyst fluid tumour markers analysis of H-MCNs remains controversial and needs more extensive sample sizes study to verify.[8, 15]
Up to now, the radiographic examination was the primary tool to diagnose H-MCNs, although with a high misdiagnosis rate.  We gathered the information (Table 1.) to find that only about half of patients with H-MCNs could be accurately diagnosed by the CT (12/26,46.1%) and MRI (8/14,57.1%), while the US was nearly no help to diagnose H-MCNs (1/29,3.4%). The characteristic features of H-MCNs are often solitary, large, thick-wall, multilocular cystic with internal septation and calcification.[10, 21] However, not all lesions simultaneously possess all of these characteristics, and some of HSC could also be described similarly, which made H-MCNs difficultly diagnosed accurately by radiography. In the current study, enhancement after contrast, septa, biliary ductal dilation were significantly associated with H-MCNs compared with HSC. What was interesting is that most lesions of H-MCNs (23/29,79.3%) were located in the left lobe of the liver, bur the normal right lobe of the liver is much bigger than the left. We also found the location of the lesion had a significant difference between H-MCNs and HSC. The mechanism of that need to be further explored.
The distinguish of H-MCNs and HSC preoperatively was crucial to the therapeutic plan. The treatment of HSC is usually fenestration or unroofing. Several patients misdiagnosed as H-MCNs could be performed radical excision and get unnecessary surgical trauma. In our institution, almost all of the fenestration surgery could be conducted by laparoscopy, and majors of patients could discharge in one or two days after the operation. However, because of the high rate of recurrence and the potential of malignant transformation, patients with H-MCNs were recommended to undergo radical resection, such as complete cyst resection or anatomical liver resection, even a liver transplant.[9, 22, 23] It was reported that complete cyst resection of H-MCNs could bring to long-term survival and a low rate of recurrence.[9, 24] According to a multi-institutional study, if the H-MCNs were performed fenestration, the recurrence could reach 48.6%, and might enhance the risk of malignant-transformation.
Since the preoperative diagnosis of H-MCNs remain quite difficult, and the treatment of H-MCNs and HSC is extraordinarily different, it is essential to establish a preoperative diagnosis model to enhance the ability to differentiate H-MCNs and HSC. Therefore, we created a diagnosis nomogram that facilitates accurate identification and screening of H-MCNs before the operation. Although many kinds of literature have investigated factors to distinguish H-MCNs and HSC, to our knowledge, no study has incorporated these independent risk factors to create a diagnosis model.[8, 15, 20] Nomogram is a visualized tool that could vividly display the logistic regression model and help to make clinical decisions. In our nomogram, three factors (Enhancement after contrast, intrahepatic location, and biliary dilation) were significantly associated with H-MCNs in multivariate logistic regression analysis and a nearly significant factor (serum CA19-9 level greater than 20 U/ml) were included. This was the first nomogram that could calculate the probability of H-MCNs in liver cystic lesions. The advantages of the nomogram were that it provides individualized risk assessment in a dynamic manner, and all the factors included are routinely reached in clinical practice. By utilizing this nomogram, the patients with a high probability of H-MCNs would be recommended to undergo a complete resection or a frozen section examination during the operation to get a better survival and a low rate of recurrence.
There were some limitations to this study. First, this was a retrospective study based on Sir Run run Shaw hospital electronic medical records with a relatively small simple. Second, the data of this study were collected in a single institution. Before the full acceptance of this nomogram, it is desirable to validate this result from other institutions. Third, because whether the cystic fluid tumour marker level can help in the diagnosis of H-MCNs remain controversial, and not all of the liver cystic lesion patients were routinely performed aspiration paracentesis, we didn’t include fluid tumour marker level as a predictive factor. Lastly, other specific markers to estimate H-MCNs might further improve the accuracy of this diagnosis prediction model.