[1546] Diagnostic Utility of Glutamine Synthetase and Serum Amyloid Associated Protein Immunohistochemistry in the Distinction of Focal Nodular Hyperplasia and Telangiectatic Hepatic Adenoma.

Nancy M Joseph, Dhanpat Jain, Tsung-Teh Wu, Matthew Yeh, Michael Torbenson, Sanjay Kakar. UCSF, San Francisco, CA; Yale Univ, New Haven, CT; Mayo, Rochester, MN; Univ of Washington, Seattle; Johns Hopkins, Baltimore, MD

Background: Telangiectatic/inflammatory hepatic adenoma(THA)can show overlapping features with focal nodular hyperplasia(FNH) including fibrous stroma,ductular reaction and inflammation.Expression of serum amyloid associated protein(SAA)in THA and map-like pattern of glutamine synthetase(GS)in FNH has been reported.We examined SAA and GS in THA and FNH to determine the specificity of these markers and to identify variant staining patterns that can lead to diagnostic errors.
Design: Morphology and immunohistochemistry for GS and SAA was reviewed in 30 FNH(18 biopsy,12 resection)and 42 THA(5 biopsy,37 resection).GS staining was classified as diffuse map-like,perivascular,perivascular with focal map-like, and diffuse.SAA was recorded as negative(0-10%),focal(10-50%)and diffuse(>50%).
Results: Diffuse map-like GS was seen in 28(93%)FNH;2 cases showed focal map-like pattern.30(71%)THA showed perivascular GS which was expanded compared to normal liver.In 8(19%)THA,perivascular staining was accompanied by interconnecting bands of positive hepatocytes focally resembling map-like pattern.Unlike FNH where areas around fibrous septa are GS-negative,GS in these 8 cases was positive around arterioles and map-like pattern was created by negativity in midzonal hepatocytes between perivenular and periarteriolar area.Diffuse GS staining was seen in 4(10%)THA and was easily distinguished from map-like GS pattern.SAA expression was seen in 38(91%)THA and 4(13%)FNH.

	Fibrous stroma	Ductular reaction	Inflammation	Telangiectasia	Steatosis
FNH(n=30)	87	87	47	27	23
T-HA(n=42)	21	50	60	83	55
p-value	< 0.001	< 0.001	0.22	< 0.001	0.005

Numbers reflect percentages

	GS Map-like	GS resembling map-like	Diffuse GS	SAA positive
FNH(n=30)	93	7	0	13
THA(n=42)	0	19	10	91
p-value	< 0.001	0.10	0.09	< 0.001

Figures reflect percentages


Conclusions: Map-like GS pattern is highly specific for FNH and is seen in nearly all cases.Majority of THA show perivascular GS similar to normal liver.Two other GS patterns in THA(perivascular with focal map-like and diffuse)can be mistaken for map-like FNH pattern.Most THA are SAA positive,but this is also seen in 17% of FNH.GS and SAA can distinguish FNH and THA with close attention to variant staining patterns.
Category: Liver & Pancreas

Monday, February 28, 2011 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 203, Monday Morning