Atypical Hepatic Mesenchymal Hamartoma: Histologic Appearance, Immunophenotype, and Molecular Findings

Abstract

Hepatic mesenchymal hamartoma is a rare benign neoplasm principally encountered in young children. Its origin is unknown. We report an unusual hepatic mesenchymal hamartoma in a 7-month-old girl, including histopathologic findings, immunophenotype, and karyotype. Chromosomal microarray analysis of tumoral tissue and circulating lymphocytes found 4 copies of a segment at 1q44 and fluorescence in situ hybridization indicated tandem triplication, ascribed to expansion of a paternal tandem duplication. This genetic abnormality may have played a role in pathogenesis.

Hepatic mesenchymal hamartoma and undifferentiated embryonal sarcoma of the liver: a pathologic review

“…It encodes a cluster of 46 microRNAs from the paternal allele. In addition, El Demellawy et al recently described an atypical HMH with a tandem triplication of chromosomal segment at chromosome 1q44 [12].…”

“…Wu et al argued that the intralesional hepatocytes are most likely to be derived from common progenitor cells and are a component of HMH rather than entrapped nonneoplastic hepatocytes [16]. The unusual presence of immature hepatocytes with extensive steatosis has also been reported [12]. Meanwhile, osseous metaplasia has been described in a case of recurrent HMH [17].…”

Mesenchymal Hamartoma of the Liver and Spleen-A Rare Pseudotumour in Adults

“…On microscopic examination, it displays all the features of the normal hepatic parenchyma, albeit with an anomalous organization [11]. Hepatic cystadenoma should be taken into consideration, as it microscopically presents as a three-layered, often mucin-producing cystic proliferation [11,12]. Malignant tumours of the liver are important entities that should be considered in the differential diagnosis of hepatic mesenchymal hamartoma, as this lesion often involves a possible association with undifferentiated hepatic embryonal sarcoma, which has been demonstrated throughout various studies [12].…”

“…Hepatic cystadenoma should be taken into consideration, as it microscopically presents as a three-layered, often mucin-producing cystic proliferation [11,12]. Malignant tumours of the liver are important entities that should be considered in the differential diagnosis of hepatic mesenchymal hamartoma, as this lesion often involves a possible association with undifferentiated hepatic embryonal sarcoma, which has been demonstrated throughout various studies [12]. Malignant transformation of HMH has been well documented in patients who have undergone surgical resection, even multiple years after the procedure [12].…”

“…Malignant tumours of the liver are important entities that should be considered in the differential diagnosis of hepatic mesenchymal hamartoma, as this lesion often involves a possible association with undifferentiated hepatic embryonal sarcoma, which has been demonstrated throughout various studies [12]. Malignant transformation of HMH has been well documented in patients who have undergone surgical resection, even multiple years after the procedure [12]. Undifferentiated embryonal sarcoma is a malignant lesion with an overall low incidence [12,13].…”