[1562] Inflammatory Pseudotumor (IPF) of Liver: An Entity Distinct from Inflammatory Myofibroblastic Tumor (IMFT): A Clinicopathologic, Immunohistochemical, and Molecular Genetic Study of 145 Cases.

Hala R Makhlouf, Julie C Fanburg-Smith, Guanghua Wang, Mahvash Mujahid, Zach Vesoulis, Zachary D Goodman. Armed Forces Institute of Pathology, Washington, DC; Inova Fairfax Hospital, Falls Church, VA

Background: Liver pseudotumors are reportedly rare, with less than 200 cases in the literature since 1953, Pack and Baker. There is confusion over these lesions; particularly since IPT has been lumped together as IMFT in the pediatric soft tissue literature. IMFT is a neoplastic process with rearrangement of ALK gene (2p23). We review our experience with hepatic IPT//IMFT.
Design: Cases designated hepatic IMFT or IPF were studied, including patient folders, slides, IHC for IgG4, lymphoid markers, ALK and molecular for ALK and EBV. 0-4+ presence of spindled and specific inflammatory cell components were recorded.
Results: 145 hepatic cases reviewed were all reclassified as IPT variant. The cases included 54F: 91M, with a mean age of 54. Races included Caucasian (n=48 known) followed by Black with fewer Hispanic and Asian. 90 cases were solitary; 40 multiple, 15 not specified; right= left sided. Patients presented with abdominal pain and fever with no known elevation of AST/ALK but mass on imaging, ranging from 0.2 to 20.5 (median, 4) cm. A few patients had known cholelithiasis/cholecystitis. Needle or wedge biopsy was performed. Histologically the lesions could be separated from surrounding liver and were composed of varying proportions of inflammatory cells with fibrosis but without a prominent spindled myofibroblastic component. The lesions were divided into five main groups: plasma cell rich with diffuse or aggregates of lymphocytes (n=67), mixed inflammatory (n=30), granulomatous (n=21), granulomatous with eosinophils (n=15), and predominantly purulent (n=12); all appeared to be resolving inflammatory processes. None of cases studied had positive staining for monoclonal lymphoid population, CD1a, IgG4 in plasma cells, WS, AFB, PAS, GMS, or ALK kinase and none of n=15 showed ALK gene rearrangement. 3/29 cases were positive for EBER in situ. Follow-up to date reveals no patients with subsequent neoplasm, recurrence or metastasis.
Conclusions: Most cases considered as IMFT in liver are better diagnosed as IPT, as a form of resolving inflammatory process. These lesions predominate in middle aged adult males who present with fever, abdominal pain, and mass and may be multiple. While EBV may account for 10% of cases, future study is warranted to delineate possible other specific organisms to hepatic IPF subtypes; there is no IgG4 positive subset to suggest autoimmune process.
Category: Liver & Pancreas

Tuesday, March 1, 2011 9:30 AM

Poster Session III # 263, Tuesday Morning


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