[1352] Significantly Increased IgG4/IgG Ratios May Be Rarely Seen in Lymph Nodes of Patients without IgG4-Related Sclerosing Disease.

Marian A Rollins-Raval, Raymond E Felgar, Alyssa Krasinskas, Christine G Roth. University of Pittsburgh Medical Center, PA

Background: IgG4-related sclerosing disease (IRSD) is a newly recognized, steroid-responsive systemic autoimmune disease characterized by mass-forming lesions with dense sclerosis and increased IgG4+ cells. Various patterns of lymph node involvement have been described: (I) Castleman disease-like, (II) follicular hyperplasia and (III) interfollicular expansion by plasma cells and immunoblasts (Am J Surg Pathol 2008;32:671-681 and Modern Pathology 2009;22: 589-99). We investigated IgG4/IgG ratios in lymph nodes showing these histologic patterns, and correlated with the clinical features to evaluate for occult involvement by IRSD.
Design: Reactive lymph nodes with the above mentioned patterns were retrieved from departmental archives. The patients had an average clinical follow up of 6.2 (range 2-12) years. Paraffin-section immunohistochemistry (IHC) stains were performed for IgG4 and IgG. The areas with the highest density of positive cells were evaluated. Three high power fields (HPF) in each section were counted, and an average number of positive cells per HPF was calculated. As previously established, a significant increase of IgG4+ cells was considered >40% of IgG4+ cells among IgG+ cells.
Results:

Pattern	IgG4 average number per HPF (range)	IgG average number per HPF (range)	IgG4/IgG average ratio % (range)
I (n=7)	4.8 (0.6-13)	131.2(29.6-342)	5.05 (1.2-19.2)
II (n=10)	8.4 (0-57.3)	159 (37.3-434)	3.75 (0-13.2)
III (n=9)	26.6 (0-185)	252.7 (68.6-629.6)	7.99 (0-54.04)

None of the Type I or Type II pattern reactive lymph nodes showed increased IgG4/IgG ratios. Only one case of the Type III pattern demonstrated an increase in IgG4/IgG ratio above 40% (54.04%), a case with Hashimoto's thyroiditis. This patient has been followed for more than eleven years at this center, and has no clinical evidence for ISRD.
Conclusions: Significantly increased IgG4/IgG ratios may rarely be seen in other autoimmune disorders outside of the clinical context of IRSD and in isolation do not establish the diagnosis of IRSD.
Category: Hematopathology

Tuesday, March 1, 2011 1:00 PM

Poster Session IV # 151, Tuesday Afternoon