Immunoglobulin G4-Related Disease (IgG4-RD) Mimicking Hyaline Vascular Castleman Disease

Abstract

Abstract Introduction/Objective Immunoglobulin G4-related disease (IgG4-RD) is a newly emerging immune-mediated fibroinflammatory disease characterized by increased IgG-4+ plasma cells. In soft tissue and visceral organs, the IgG4+ plasma cells often accompany a storiform pattern of fibrosis with obliterative phlebitis. In lymph nodes, rare cases have been described in the literature mimicking Multicentric Castleman Disease. Methods/Case Report Herein, we present a case of a 59-year-old male with history of lung adenocarcinoma status post resection one year prior, who presented with several months of unintentional weight loss and worsening of cervical lymphadenopathy. CT scan of the neck demonstrated extensive cervical lymphadenopathy. Incidentally, patient had traveled to a foreign country and had a positive QuantiFERON result. Clinical suspicion was either nodal metastatic disease or TB infection. An excisional biopsy of the left cervical lymph node was performed. Microscopic examination revealed numerous hyperplastic follicles with significant hyaline deposition, concentrically thickened mantle zones, radially penetrating vessels, increased interfollicular vascularity and plasmacytosis; morphologic features commonly associated with Hyaline-Vascular Castleman Disease (HVCD). Additionally, plasmacytosis within germinal center was identified. Immunohistochemical stains demonstrated significant IgG4+ plasma cells (approaching 108/HPF) within the germinal centers. All plasma cells were polytypic. Results (if a Case Study enter NA) N/A. Conclusion Commonly described patterns for IgG4-RD in the literature are multicentric Castleman disease (MCD)-like, whereas, in our case, we present intrafollicular plasma cell proliferation pattern of IgG4-RD with classic background features of HVCD. Accurate diagnosis and distinction between these two entities is imperative for prognostication, treatment and clinical management of IgG4-RD.