[1804] Is Low-Grade Lymphomatoid Granulomatosis an IgG4-Related Interstitial Lung Disease?

CJ Holman, J Jessurun, JG Strickler, SE Pambuccian. University of Minnesota, Minneapolis, MN; Abbott Northwestern Hospital, Minneapolis, MN

Background: Lymphomatoid granulomatosis (LYG) of the lung is a rare B-cell lymphoproliferative disorder, that is usually Epstein-Barr virus (EBV)-positive, often accompanied by an exuberant reactive perivascular infiltrate with a predominance of T-cells, and a variable number of plasma cells. Recently Yamashita et al (Am J Surg Pathol 2008;32(11):1620-6) described 3 cases of lung involvement by IgG4-related disease showing a histology reportedly indistinguishable from grade 1 lymphomatoid granulomatosis (LYG-G1). These authors suggest that given the absence or paucity of EBV-positive cells, atypia, and monoclonality, what has been described as LYG-G1 may not be part of the spectrum of LYG-G2/G3 and may instead correspond to IgG4-related lung disease. The aim of this study was to establish if cases of low grade LYG diagnosed at our institution would fulfill the criteria for IgG4-related lung disease.
Design: All cases diagnosed as pulmonary LYG-G1 or LYG-G2 or IgG4-related lung disease in our institution between 1996-2009 were retrieved through an electronic database search, and the slides reviewed. Diagnosis and grading of LYG were performed according to the 2008 WHO criteria. CD138, IgG4, CD20, and CD3 immunostains as well as EBER ISH were performed on all cases. The density of plasma cells was estimated by counting the number of CD138+ plasma cells in four 40x field "hot-spots". The number of IgG4-staining cells was counted in the same spots and the ratio of IgG4/CD138-staining plasma cells was calculated.
Results: 6 cases of pulmonary LYG (3 grade 1, 3 grade 2) from patients aged 48-80, M/F=2/4 and one case of IgG4-related lung disease were identified. The IgG4-related lung disease had a histologic pattern similar to LYG-G1. No IgG4-positive plasma cells were identified in any of the LYG cases but over 30% of plasma cells were IgG4+ in the single case diagnosed as IgG4-related lung disease.

Age/SexEntityEBER/HPFClusters of large B-cellsCD138 countIgG4/CD138
65 MIgG4-related0no17432%
65 FLYG-G1<3no10
53 MLYG-G1<3no42.50
80 FLYG-G11no67.50
48 FLYG-G219no72.50
64 FLYG-G210yes130
65 MLYG-G215yes450

Conclusions: Our results support the existence of LYG-G1 as an entity separate from IgG4-related lung disease. However, in cases of LYG-G1 pattern that are EBV negative, a IgG4 immunostain should be performed to evaluate for the possibility of IgG4-related lung disease.
Category: Pulmonary

Tuesday, March 23, 2010 1:00 PM

Poster Session IV # 256, Tuesday Afternoon


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