Acute respiratory distress syndrome following resection of a mesenchymal hamartoma of the liver

Management of benign liver tumors

Benign liver tumors in children are far less frequent than their malignant counterparts. Recently, there have been advances of diagnostic procedures and novel treatments with improved classification as a result. While malignant pediatric liver tumors have been comprehensively addressed by multicenter international tumor trials, benign tumors have more usually relied upon individualised workup and treatment. Due to the rarity and heterogeneity of these different entities, large studies are lacking. In this article the authors highlight the spectrum of benign liver tumors with special focus on specific clinical features, pathology, and treatment.

Rare benign tumors of the liver: still rare?

Background

Benign liver tumors are common. They do not spread to other areas of the body, and they usually do not pose a serious health risk. In fact, in most cases, benign liver tumors are not diagnosed because patients are asymptomatic. When they are detected, it’s usually because the person has had medical imaging tests, such as an ultrasound (US), computed tomography (CT) scan, or magnetic resonance imaging (MRI), for another condition.

Materials and methods

A search of the literature was made using cancer literature and the PubMed, Scopus, and Web of Science (WOS) database for the following keywords: “hepatic benign tumors”, “hepatic cystic tumors”, “polycystic liver disease”, “liver macroregenerative nodules”, “hepatic mesenchymal hamartoma”, “hepatic angiomyolipoma”, “biliary cystadenoma”, and “nodular regenerative hyperplasia”.

Discussion and conclusion

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in some areas of the world; there is an increasing incidence worldwide. Approximately 750,000 new cases are reported per year. More than 75 % of cases occur in the Asia-Pacific region, largely in association with chronic hepatitis B virus (HBV) infection. The incidence of HCC is increasing in the USA and Europe because of the increased incidence of hepatitis C virus (HCV) infection. Unlike the liver HCC, benign tumors are less frequent. However, they represent a chapter always more interesting of liver disease. In fact, a careful differential diagnosis with the forms of malignant tumor is often required in such a way so as to direct the patient to the correct therapy. In conclusion, many of these tumors present with typical features in various imaging studies. On occasions, biopsies are required, and/or surgical removal is needed. In the majority of cases of benign hepatic tumors, no treatment is indicated. The main indication for treatment is the presence of significant clinical symptoms or suspicion of malignancy or fear of malignant transformation.

Placental mesenchymal dysplasia associated with hepatic mesenchymal hamartoma in the newborn

Placental mesenchymal dysplasia is an uncommon disorder in which the placenta is enlarged with abnormal, large, and often cystic villi with dilated and/or thick-walled vessels. These placental changes can mimic a partial hydatidiform mole but in contrast to a partial mole can coexist with a fully viable fetus. Fetal anatomical and vascular anomalies frequently coexist with placental mesenchymal dysplasia. In this case, placental mesenchymal dysplasia was associated with preterm labor at 33 weeks' gestation, fetal compromise, and a large abdominal mass with a large hepatic cyst that was de-roofed at exploratory laparotomy. The neonate remained critically ill with hypoxic ischaemic encephalopathy and coagulopathy and died despite intensive care. Biopsy and autopsy findings showed a large cystic mesenchymal hamartoma affecting the left lobe of the liver. This appears to be the 3rd histologically confirmed association of placental mesenchymal dysplasia with mesenchymal hamartoma of the liver in the English language literature.

Neonatal liver tumours

Primary liver tumours are very rare during the neonatal period, but increasing numbers of them are now diagnosed prenatally by routine ultrasound scan. A precise diagnosis is sometimes problematic because of non-specific clinical symptoms, misleading imaging and difficulties with histological interpretation. Benign infantile haemangioendothelioma usually undergoes spontaneous regression, but may be life-threatening due to congestive heart failure and/or consumptive coagulopathy when treatment with resection, embolization or arterial ligation is necessary. Malignant hepatoblastoma may occur in the newborn, and often has to be treated with chemotherapy to achieve resectability. Symptoms are less specific and the prognosis is worse than in older children. Mesenchymal hamartoma is a benign cystic lesion that should be resected whenever possible. Rarely, germ cell tumours occur in the neonatal liver. Benign teratomas have to be resected, while malignant choriocarcinomas may respond to chemotherapy and can be cured in some cases.

Chromosomal translocation in mesenchymal hamartoma of liver: what is its significance?

Mesenchymal hamartoma of the liver is generally considered to be benign in nature, and surgical excision has been the treatment of choice. There have been 3 reports on the association of cytogenetic abnormalities with this tumor, and the possibility of malignant potential has been raised. The authors report a fourth case with a previously unreported complex chromosomal translocation between chromosomes 11, 17, and 19 at bands q12, p11, and q13.3, respectively in all cells examined and discuss the significance of this finding.

Mesenchymal hamartoma of the liver--new insight into histogenesis

BACKGROUND/PURPOSE

Mesenchymal hamartoma (MH) of the liver is thought to develop from the ductal plates of the prenatal liver. This immunohistochemical study was performed to gain insight into the pathophysiology of its development.

METHODS

Specimens from four MHs with adjacent liver, in one case from a biopsy and from the resected lesion after 6 years follow-up, were investigated with immunostaining on cryostatsectionswith antibodies against cytokeratins, vimentin, desmin and alpha-actin, as well as von Willebrand factor (factor VIII), fibroblast growth factor (FGF) receptors, FGF-1 (acidic FGF), FGF-2 (basic FGF), and the proliferation-associated Ki67 antigen.

RESULTS

Fibrous tissue of MH stained positive not only for vimentin, but also for desmin and alpha-actin, whereas cytokeratins and factor VIII showed specific staining in biliary cysts and endothelial cells, respectively. All mesenchymal cells expressed proteins of the FGF receptor family. Although FGF-1 was only scarcely detectable, there was an accumulation of FGF-2 in borderline areas of liver to MH. Multiple Ki67-positive mesenchymal cells could be identified in these regions in all three MHs. However, we could not detect any proliferative activity in the MHs after follow-up.

CONCLUSIONS

The proliferative process in MH is still active during early childhood. FGF-2 may have a role in promoting this process. The positivity for desmin and alpha-actin of the lesions suggests that fat-storing (Ito) cells of the immature liver may be involved in the development of MH.