Immunostaining of glutamine synthetase is a sensitive and specific marker for diagnosing focal nodular hyperplasia in needle biopsy

SummaryAimsFocal nodular hyperplasia (FNH) has characteristic histological features which may not be seen in needle biopsy specimens. We investigate the diagnostic role of glutamine synthetase (GS) in needle biopsy specimens.MethodsSixty-one hepatic tumours were categorised into 20 ‘definite’ FNHs, 13 ‘probable’ FNHs, and 28 cases without specific diagnosis. Needle biopsy specimens of 92 non-tumourous lesions, 25 well-differentiated hepatocellular carcinomas (WDHCCs), and 4 high-grade dysplastic nodules (HGDNs) and resection specimens of 10 macroregenerative nodules were also selected for immunohistochemical stain of GS for comparison.ResultsAll 20 ‘definite’ FNHs, nine ‘probable’ FNHs, and five cases without specific diagnosis expressed typical maplike staining pattern of GS. The demographic data of these five cases were similar to those of FNH. All cases of chronic hepatitis B and C, cirrhosis, macroregenerative nodule and peritumourous liver tissue showed normal pericentral/ periseptal pattern. Fifteen of 25 WDHCCs and one HGDN showed diffuse pattern. Ten WDHCCs and two HGDNs showed negative staining. One HGDN showed mosaic pattern.ConclusionsImmunohistochemical staining of GS increases the diagnostic sensitivity of FNH in needle biopsy, especially in those without typical morphology. It also helps in differentiating FNH from other tumourous and non-tumourous lesions.