Clinical characteristics of a concurrent condition of IgG4-RD and Castleman's disease.

IgG4-related disease (IgG4-RD) and Castleman's disease (CD) share similar clinical manifestations. When the histopathology coincides with the diagnosis of both IgG4-RD and CD, it is hard to depart the two disease entities utterly; here we call it IgG4-CD provisionally. In this study, we aim to review the clinical features of IgG4-CD. This study is based on a retrospective analysis of a prospectively acquired database. IgG4-CD was defined histopathologically in patients who fulfilled the diagnosis of both IgG4-RD and CD. Forty-five definite IgG4-RD and 16 multicentric CD (MCD) patients were recruited as controls. Clinical features including organ involvement, serum IgG4, IgG, IgE, ESR, CRP, and IL-6 levels were collected and analyzed. Fifteen patients (2.8%) out of 534 patients with IgG4-RD in China's largest prospective IgG4-RD and Mimicry cohort fulfilled the definition of IgG4-CD. There were 14 males and 1 female, whose mean age was 47 ± 18 years old, and the median disease duration before diagnosis was 12 (1-132) months. Eight patients have allergic disease history. IgG4-CD patients had more lymph node involvement (100 vs 57.8%, P < 0.01), while IgG4-RD patients had more submandibular (33.3 vs 77.1%, P < 0.01) and parotid gland (13.3 vs 40.9%, P < 0.05) affected. IgG4-CD patients had significantly higher levels of ESR, CRP, IgG, IgG1, IgG3, IgG4, and IgE than IgG4-RD patients. Compared with MCD patients, IgG4-CD patients showed higher incidence of salivary gland and paranasal sinus involvement, higher hemoglobin, eosinophil count, serum IgG4 level and IgG4/IgG ratio, and lower CRP, IL-6 levels, and IgG1/IgG, IgG2/IgG ratio. All patients with IgG4-CD exhibited relatively favorable outcomes. Both IgG4-RD and CD can involve multiple organs. There are a small group of patients who had clinical and pathological characteristics of both CD and IgG4-RD showed better clinical outcome. In the long-term prognosis of these patients, the relationship of CD and IgG4-RD is waiting to be further elucidated.