Background IgG4-related disease (IgG4-RD) is a fibro-inflammatory disease with multiple-organ involvement characterized by infiltration of IgG4+plasma cells and elevated serum IgG4 concentrations. However, similar findings are observed in multicentric Castleman's disease (MCD)1, thereby making it difficult to differentiate one disease from the other.
Objectives The aim of this study was to clarify the differences of clinical characteristics and laboratory findings in IgG4-RD and MCD for differential diagnosis.
Methods All consecutive patients with IgG4-RD and MCD who visited the Rheumatology or Hematology department in our institutes from January 2000 to November 2015 were retrospectively reviewed. Patient characteristics and laboratory data at the time of diagnosis were compared.
Results Forty-nine patients with IgG4-RD and 48 patients with MCD were included. Patients with IgG4-RD were older compared to MCD (57.4 vs 47.3 years, p<0.0001) and there was no difference in gender distribution. While lymph nodes were affected less frequently in IgG4-RD compared to MCD (49% vs 100%, p<0.0001), lacrimal glands, salivary glands and pancreas were affected only in IgG4-RD. The levels of serum IgG, IgA and IgM were significantly lower in patients with IgG4-RD compared to MCD (IgG: 1945.6 mg/dl vs 4317.5 mg/dl, p<0.0001, IgA: 172 mg/dl vs 669 mg/dl, p<0.0001, IgM: 83 mg/dl vs 279 mg/dl, p<0.0001), whereas no difference was observed in serum IgE levels. Although level of serum IgG4 was also equivalent between IgG4-RD and MCD (607 mg/dl vs 353 mg/dl, p=0.211), IgG4/IgG ratio was significantly higher in IgG4-RD compared to MCD (0.30 vs 0.09, p<0.0001). In addition, atopic history was more frequent (71.4% vs 16.7%, p<0.0001), and the proportion of eosinophils (6.4% vs 2.7%, p<0.0001) was significantly higher in IgG4-RD compared to MCD. The level of serum C-reactive protein (0.3 mg/dl vs 5.4 mg/dl, p<0.0001) and erythrocyte sedimentation rate (35.9 mm/hr vs 110.7 mm/hr, p<0.0001), the prevalence of anemia (10.2% vs 50.0%, p<0.0001) and thrombocytosis (2.0% vs 31.3%, p<0.0001) were significantly higher in MCD compared to IgG4-RD.
Conclusions The involvement of lacrimal gland, salivary gland and pancreas was unique for IgG4-RD. While allergic reaction such as hypereosinophilia and atopic history was more frequently observed in IgG4-RD, intense inflammation was the distinct characteristics for MCD. The distribution of organ involvement and marked inflammatory reaction represented by elevated serum CRP, anemia and thrombocytosis were important features to distinguish between IgG4-RD and MCD.
Y. Sato et al. Systemic IgG4-related lymphadenopathy: a clinical and pathologic comparison to multicentric Castleman's disease. Mod Pathol 2009;22:589–599.
Acknowledgement We sincerely thank all the physicians and others caring for the patients enrolled in this study.
Disclosure of Interest None declared
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