A Limited Immunohistochemical Panel Can Subtype Hepatocellular Adenomas for Routine Practice.

Abstract

β-Catenin-activated hepatocellular adenomas have an elevated risk of harboring foci of hepatocellular carcinoma. Inflammatory adenomas also have an increased propensity for malignant transformation and are associated with a systemic inflammatory syndrome. Patients with these two adenoma subtypes benefit from excision. We assessed whether β-catenin-activated and inflammatory adenomas could be identified using a limited immunohistochemical panel. Forty-six adenomas were assessed by morphology and β-catenin, serum amyloid A, and glutamine synthetase immunostains. Morphologic examination produced a morphologic working diagnosis of inflammatory adenoma in 25 (54%) of 46 cases, β-catenin-activated adenoma in three (7%) of 46 cases, and 18 (39%) of 46 cases of other adenomas. After immunohistochemical staining, the morphologic diagnosis was confirmed in 15 (33%) of 46 and changed in 20 (43%) of 46, for a final distribution of 16 (35%) of 46 inflammatory adenomas, four (9%) of 46 β-catenin-activated adenomas, seven (15%) of 46 β-catenin-activated inflammatory adenomas, and 19 (41%) of 46 other adenomas. Inflammatory and β-catenin-activated adenomas were readily identified by immunostaining patterns. These findings reinforce the necessity of immunohistochemistry in classifying adenomas, as assessing morphology alone often provided inaccurate subclassification. β-Catenin-activated and inflammatory adenomas can be accurately diagnosed using only a limited panel of widely available immunostains.