Solid mesenchymal hamartoma of the liver in adult

Liver Transplant for Adult Recurrent Hepatic Mesenchymal Hamartoma and a Feasible Treatment Modality: A Case Report and Literature Review

BACKGROUND

Adult hepatic mesenchymal hamartoma (HMH) is an extremely rare hepatic tumor. Recurrence following complete resection is uncommon. Liver transplantation (LT) is described as a possible treatment option in nonresectable HMH. We conducted a systematic review investigating LT in adult HMH followed by a case report describing evidence of extensive recurrence following complete resection of large right-sided HMH requiring LT.

CASE REPORT

A 46-year-old woman with symptomatic large right-hepatic HMH underwent right hemi-hepatectomy with histologic evidence of complete resection. Two and a half years postresection, she presented with abdominal pain and distension; imaging revealed large multi-septated hepatic cystic lesions within the liver suggestive of extensive recurrence of disease with concerns of malignant sarcomatous transformation. After a multidisciplinary team discussion, the lesion was deemed unresectable and the patient was referred for LT. Findings on transplantation included giant multiple hepatic cystic lesions occupying the entire abdomen and histopathological analysis confirmed recurrent HMH with no malignancy. The 6-month follow-up was unremarkable with no signs of postoperative complications or rejection.

CONCLUSION

We identified only 3 reported adult unresectable HMH cases in the English literature requiring LT, with good clinical outcome and no rejection on a 1-year follow-up. To our knowledge, we report the first recurrent HMH that required LT in the English literature. Current evidence suggests possible malignant sarcomatous transformation of those lesions. No guidelines exist on postresection surveillance for HMH; however, given their malignant potential, we suggest a benefit of imaging-based surveillance following HMH resection. Offering LT for nonresectable or recurrent HMH is a feasible treatment modality with a reported good outcome.

Mesenchymal Hamartoma of the Liver in Older Children: An Adult Variant or a Different Entity? Report of a Case With Review of the Literature

Mesenchymal hamartoma of the liver (MHL) is an uncommon benign hepatic tumor typically affecting children under 2 years of age. Only 5% of MHL occur after 5 years and are very rarely observed in adults. According to age, MHL may differ in their morphologic features. We report a case of an 11-year-old boy with MHL, resembling a malignant lesion from a clinical point of view, characterized by unusual histologic features: a prominent myxoid stroma, with a minimal ductular component, and absent cystic spaces. The present case and others reported in older children or adults demonstrate that these lesions may represent a potential diagnostic pitfall when occurring outside their classic clinical context especially because of their peculiar histologic findings. Moreover, it may be hypothesized that variation in morphology might be related to different evolutive stages of the cell of origin. To support this hypothesis, we therefore studied the presence of components of the Notch pathway inside and outside the lesion. Their absence inside the tumor and, in contrast, the expression of Notch2 and HES1 evident in overrepresented bile ducts present at the periphery might explain not only the lack of bile ducts, but also indicate a more adult phenotype compared with classic pediatric MHL, which show more bile ducts and liver trabeculae embedded in the mesenchymal matrix.

Adult hepatic mesenchymal hamartoma: an unusual case

Mesenchymal hamartoma is a benign hamartomatous lesion with unknown histogenesis. It generally occurs in pediatric population and has been rarely reported in adults. We report an unusual case of a cystic mesenchymal hamartoma of liver in an 81-year-old elderly male. A provisional diagnosis of liver abscess was made and definitive histopathology confirmed the diagnosis. This case has been reported because of its rarity.

Adult Mesenchymal Hamartoma of the Liver: Case Report and Literature Review

Mesenchymal hamartoma of the liver (MHL) is a rare benign lesion occurring primarily in the pediatric population. While the precise pathogenesis of the tumor is not certain, the most common theory relates to aberrant mesenchyme development in the portal tract likely related to the bile ducts. A 53-year-old female was evaluated for an incidental liver mass. Initial CT scan showed a cystic lesion in the right lobe of the liver and follow-up imaging revealed an increase in size and the percent solid component within the mass. In view of these changes, a nondiagnostic biopsy was obtained followed by extirpation of the lesion. Gross pathological review of the lesion identified a 9 × 9 × 7.5 cm, pink-yellow-tan, gelatinous mass, with a >1 cm clear surgical margin. Histologically, the mass consisted of benign dilated bile ducts, as well as myxoid stroma with spindle cells showing smooth muscle differentiation. The patient was discharged home on postoperative day five. A review of the literature for MHL in adults reports 30 previous cases, predominantly published as individual case reports describing the size, lobe(s) of the liver affected, and the cystic/solid nature of the tumor. MHL in adults may represent a potentially premalignant lesion, as the emerging literature supports a potential relationship between MHL and malignant undifferentiated embryonal sarcoma in regards to cytogenetic analysis. Aggressive surgical management of MHL in adults is mandated when feasible.

Radiological spectrum of hepatic mesenchymal hamartoma in children

Objective

A hepatic mesenchymal hamartoma is an uncommon benign tumor in children and little is known about the spectrum of its radiological features. The purpose of this study is to describe the spectrum of radiological features of a hepatic mesenchymal hamartoma in children.

Materials and Methods

Thirteen children with a pathologically confirmed hepatic mesenchymal hamartoma (M:F = 7:6; mean age, 3 years 2 months) were included in our study. Ultrasonography (US) was performed in nine patients including color and power Doppler US (n = 7). CT scans were performed in all patients. We evaluated the imaging findings of the hepatic mesenchymal hamartomas and the corresponding pathological features.

Results

Each patient had a single tumor (mean diameter: 13 cm [1.8-20 cm]). On CT and/or US, four patients (31%) had a "multiseptated cystic tumor", five patients (38%) had a "mixed solid and cystic tumor", and four patients (31%) had a "solid tumor." The septa of the cystic portion were thin in the multiseptated cystic tumors and irregularly thick in the mixed solid and cystic tumors as seen on US. On a post-contrast CT scan, solid portions or thick septa of the tumors showed heterogeneous enhancement. The amount of hepatocytes was significantly different among the three tumor groups according to the imaging spectrum (p = 0.042).

Conclusion

A hepatic mesenchymal hamartoma in children can show a wide spectrum of radiological features, from a multiseptated cystic tumor to a mixed solid and cystic tumor, and even a solid tumor.

Solid mesenchymal hamartoma in an adult: a case report

Mesenchymal hamartoma of the liver (MHL) is an uncommon tumour composed of architecturally abnormal bile ducts in an uncommitted myxoid stroma. Most MHL are diagnosed in childhood and few cases have been reported in adults. This report describes a case of a well defined solid mass in the right lobe of the liver in a 51 year old man. Preoperative radiological examination revealed a large completely solid mass. Biopsy showed a dense fibrous stroma with hyalinisation and some bile ducts. A provisional diagnosis of MHL was made. Surgical excision was impossible and liver transplantation was undertaken. Definitive pathology confirmed the diagnosis. Review of published reports shows this to be the fourth case of MHL treated by liver transplantation.

Mesenchymal hamartoma of the liver in adulthood: immunohistochemical profiles, clinical and histopathological features in two patients

Mesenchymal hamartoma is an uncommon cystic mass of the liver which occurs primarily in children. There are a few reports of its occurrence in adulthood. Here, we present two cases in female patients, 54 and 51 years old. Radiological examinations in both patients showed multiple cystic lesions in the liver. Surgically, total cystectomy was performed in the first patient, while an unroofing procedure was done in the second patient (due to misdiagnosis of the lesion as a simple cyst of the liver). On microscopic examinations of the lesion in each patient, a multilocular cyst was observed, lined by flattened epithelium and surrounded by a mesenchymal component composed of mature connective tissue, arterial and venous vascular structures, peripheral nerve bundles, and ductal structures. An immunohistochemical panel consisting of desmin, smooth-muscle actin, S-100, vimentin, CD34, carcinoembryonic antigen, pancytokeratin, cytokeratin 7, cytokeratin 8, cytokeratin 17, cytokeratin 18, cytokeratin 19, and cytokeratin 20 was applied to paraffin sections. Immunoreactivity for cytokeratin 7 and cytokeratin 19 was observed in cystic epithelium and ductal structures. Focal and patchy desmin immunoreactivity was observed in connective tissue. S-100 was positive only in peripheral nerve bundles. In conclusion, mesenchymal hamartoma of the liver in adulthood is a localized tumoral abnormality that precedes birth, and which has delayed clinical presentation. These lesions seems to be related to a maturation process. During this period of maturation, immature edematous stroma rich in mucopolysaccharides may convert to mature paucicellular hyalinized connective tissue. This maturation process may be also related to loss of premalignant potential of these tumors.

Mesenchymal hamartoma of the liver in the adult: association with distinct clinical features and histological changes

Mesenchymal hamartoma of the liver (MHL) is an uncommon mass lesion composed of architecturally abnormal bile ducts in an uncommitted myxoid stroma. Most MHL are diagnosed in childhood. More than 50% of cases are seen in the first year of life, although a few cases have been previously reported in adults. The spectrum of pathological findings in the cases presenting in adults, including differences in comparison with MHL in children, has not been fully characterized. In this report, we describe 3 cases of MHL in patients 46, 63, and 66 years of age. Each of the patients was a woman who had a solid or multicystic hepatic mass ranging from 5 to 24 cm in maximum dimension. In contrast to the childhood cases, the stromal component was fibrotic with areas of dense hyalinization and only focal myxoid areas. In 1 case, the mesenchymal component was the predominant feature of the lesion, with only occasional ductal elements identified with thorough tissue sampling. Immunohistochemical analysis with a panel of antibodies showed that, as in normal bile ducts, the ductal structures within the lesion were immunoreactive for cytokeratin 7 and negative for cytokeratin 20. The stroma was composed of a prominent population of fibroblasts and myofibroblasts that were positive for smooth muscle actin and vimentin. Analysis of the current findings, together with the previous case reports, shows that in contrast to MHL in children, this lesion in adults is found more commonly in women who present with abdominal pain. Recognition of the clinicopathologic differences between adult and pediatric cases will facilitate accurate diagnosis of this uncommon lesion.