Published in:
01-08-2014 | Case Report
Diffuse glutamine synthetase overexpression restricted to areas of peliosis in a β-catenin-activated hepatocellular adenoma: a potential pitfall in glutamine synthetase interpretation
Authors:
Ryan S. Berry, Rama R. Gullapalli, Jin Wu, Katherine Morris, Joshua A. Hanson
Published in:
Virchows Archiv
|
Issue 2/2014
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Abstract
Hepatocellular adenomas have recently been classified into four subtypes based on molecular findings: hepatocyte nuclear factor 1α (HNF1α) inactivated, inflammatory/telangiectatic, β-catenin activated, and unclassifiable. β-catenin-activated adenomas have the potential for malignant transformation and are thus important to recognize. Diffuse glutamine synthetase immunohistochemical positivity has been shown to be a reliable surrogate marker for β-catenin activation, though variations in staining patterns may be difficult to interpret. We report a case of a peliotic adenoma that was morphologically consistent with a β-catenin wild-type hepatocellular adenoma but harbored a β-catenin mutation by molecular analysis. The tumor lacked nuclear β-catenin positivity and demonstrated a hitherto undescribed pattern of glutamine synthetase overexpression restricted to areas of peliosis with mostly negative staining in non-peliotic areas. This pattern was initially interpreted as physiologic and may represent a potential pitfall in glutamine synthetase interpretation.