title: Mesenchymal Hamartoma of the Liver in Older Children: An Adult Variant or a Different Entity? Report of a Case With Review of the Literature.
abstract: 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.
authors.affiliation: *Pediatric Surgery, Departments of Pediatrics and Gynaecology-Obstetrics †Liver Transplant and Hepatobiliary Surgery Unit, Department of Surgery and Organ Transplants ‡Department of Medical and Diagnostic Sciences and Special Therapies, University of Padua, Padua, Italy.
authors.forename: Calogero
authors.initials: C
authors.lastname: Virgone
authors.forename: Giovanni
authors.initials: G
authors.lastname: Cecchetto
authors.forename: Patrizia
authors.initials: P
authors.lastname: Dall'Igna
authors.forename: Giovanni Franco
authors.initials: GF
authors.lastname: Zanon
authors.forename: Umberto
authors.initials: U
authors.lastname: Cillo
authors.forename: Rita
authors.initials: R
authors.lastname: Alaggio
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism; D001652:Bile Ducts / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D002648:Child; D002675:Child, Preschool; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006222:Hamartoma / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology / Q000601:surgery; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008099:Liver / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D008113:Liver Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D051883:Receptor, Notch2 / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D000072056:Transcription Factor HES-1
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D018398:Homeodomain Proteins; D051883:Receptor, Notch2; D000072056:Transcription Factor HES-1; C497764:NOTCH2 protein, human; C078493:HES1 protein, human