Virgone Calogero, Cecchetto Giovanni, Dall'Igna Patrizia, Zanon Giovanni Franco, Cillo Umberto, Alaggio Rita
*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.
Appl Immunohistochem Mol Morphol. 2015 Oct;23(9):667-73. doi: 10.1097/PAI.0b013e31826b56ae.
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.
肝间叶性错构瘤（MHL）是一种罕见的肝脏良性肿瘤，通常发生于2岁以下儿童。仅有5%的MHL发生于5岁以后，在成人中极为罕见。根据年龄不同，MHL的形态学特征可能有所差异。我们报告一例11岁男孩的MHL病例，从临床角度看类似恶性病变，其具有不寻常的组织学特征：显著的黏液样间质，导管成分极少，且无囊腔。本病例以及其他报道的大龄儿童或成人病例表明，当这些病变发生在其经典临床背景之外时，可能构成潜在的诊断陷阱，尤其是因其特殊的组织学表现。此外，可以推测形态学上的差异可能与起源细胞的不同演化阶段有关。因此，为支持这一假说，我们研究了病变内外Notch信号通路成分的存在情况。肿瘤内部不存在这些成分，相反，在周边过度增生的胆管中Notch2和HES1明显表达，这不仅可以解释胆管的缺失，还表明与经典小儿MHL相比具有更成熟的表型，经典小儿MHL在间充质基质中可见更多的胆管和肝小梁。
