A Subset of Rosai-Dorfman Disease Cases Exhibit Increased IgG4 Positive Plasma Cells, Another Red Herring?
Madhu P Menon, Moses O Evbuomwan, Juan Rosai, Elaine S Jaffe, Stefania Pittaluga. Laboratory of Pathology, National Cancer Institute/National Institutes of Health, Bethesda, MD; Centro Consulenze Anatomia Patologica Oncologica, Milano, Italy
Background: Sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease) is a disease of unknown etiology caused by a proliferation of non-clonal S100+ histiocytes. It occurs predominantly in the young (median age, 20) presenting either in lymph nodes or extranodal sites. Several observations about increased IgG4 positive cells in Rosai-Dorfman disease have been made previously, either through case reports or smaller case series restricted to certain anatomic sites. We sought to address this question through a larger cohort of cases with a wide age and anatomic site (nodal and extranodal) distribution.
Design: 36 cases (17 nodal,19 extranodal) were identified from consultation files of the authors' Institution between 2005 and 2011. An additional 30 cases (15 nodal,15 extranodal) were obtained from Rosai-Dorfman registry. The numbers of IgG4 and IgG positive cells were obtained after averaging three high power fields (40x) with the highest density.
Results: Median age was 35 years (range, 5 mths-82 yrs). 14 cases (21%) had increased IgG4 positive cells (Table 1). 10 cases (15%) had >50 IgG4+cells/hpf and >40% IgG4/IgG cells. The median age was significantly higher in the IgG4+ cases; 54 (range, 27-78 yrs) (p<0.05). The IgG4+ cases involved both nodal and extranodal sites, similar to IgG4- cases. Plasma cells were polyclonal in the IgG4+ cases studied (8/14).
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