The Expression of IgG and IgG4 in Lymphoma

Abstract

Objectives: Although IgG4-related disease has been gradually recognized, its relationship with malignant diseases, especially lymphoma has been an eternal topic. Therefore we set out to explore the expression of IgG4 positive cells in lymphoma. Methods: Surgical excision specimens with definite diagnosis of lymphoma from January to December, 2013 were collected. Hematoxylin-eosin staining and immunohistochemical staining of IgG and IgG4 were then evaluated on dense lymphoplasmacytic infiltration, storiform fibrosis and obliterative phlebitis. For the quantification of IgG and IgG4 positive cells, the areas with the highest density of positive cells were evaluated. Three high-powered fields (hpf) in each section were analyzed, and the average number of positive cells per hpf was calculated. Results: 16 patients with lymphoma were included in our study. There were 9 males and 7 females with an average age of 51 years old. 3 cases were diagnosed as Hodgkin lymphoma while 13 were non-Hodgkin lymphoma (diffuse large B cell lymphoma 8 cases, small B cell lymphoma 2 cases, mucosa associated lymphoid tissue marginal zone B cell lymphoma (MALToma) 1 case, follicular lymphoma, peripheral T-cell lymphoma and hepatosplenic T-cell lymphoma 1 case. Dense lymphocytic infiltration accompanied by atypical lymphocytes was observed in all the specimens. Proliferation of fibrous tissue was only seen in one specimen. IgG positive cells were detectable in 14 cases with the highest cell count from 20-350/hpf. 2 Hodgkin lymphoma cases showed of IgG4 positivity with the highest cell counts were 11 and 12/hpf respectively. Conclusion: IgG4 positive cells, fibrosis and obliterative phlebitis barely appeared in lymphoma. In combination with specific tumor signature molecules, it may not be difficult to distinguish lymphoma from IgG4-related disease.