IL-6 expression helps distinguish Castleman's disease from IgG4-related disease in the lung.

It is difficult to distinguish between multicentric Castleman's disease (MCD) and IgG4-related lung disease (IgG4-LD), an IgG4-related disease (IgG4-RD) in the lung. We focused on IL-6, which is elevated in MCD, to distinguish between MCD and IgG4-LD by RNAscope, a highly sensitive RNA in situ method. Six cases of MCD and four cases of IgG4-LD were selected. In all cases of MCD and IgG4-LD, 10 or more IgG4-positive cells were found in one high-power field. All MCD cases were inconsistent with the pathological IgG4-related comprehensive diagnostic criteria, but 2 of 6 cases had an IgG4/IgG ratio greater than 40%. In all IgG4-LD cases, histological features were consistent with the pathological IgG4-RD comprehensive diagnostic criteria. IL-6 expression was observed in all MCD and IgG4-LD cases except for one IgG4-LD biopsy. IL-6-expressing cells were mainly identified in the stroma. Sites of IL-6 expression were not characteristic and were sparse. IL-6 expression tended to be higher in MCD compared with IgG4-LD. A positive correlation was found between the IL-6 H-score and serum IL-6 level. Differences in IL-6 expression may help distinguish between MCD and IgG4-LD. In addition, the presence of high IL-6 levels may help elucidate the pathological mechanisms of IgG4-LD.

Kinugawa Y ，Uehara T ，Iwaya M ，Asaka S ，Kobayashi S ，Nakajima T ，Komatsu M ，Yasuo M ，Yamamoto H ，Ota H ... -  《BMC Pulmonary Medicine》

Immunoglobulin G4-related disease and idiopathic multicentric Castleman's disease: confusable immune-mediated disorders.

IgG4-related disease (IgG4-RD) and idiopathic multicentric Castleman's disease (iMCD) are both rare systemic immune-mediated disorders. However, the pathogenesis differs markedly between the two diseases and differing therapeutic strategies are adopted: IgG4-RD is treated using a moderate dose of glucocorticoids or rituximab, while iMCD therapy involves an IL-6-targeted approach. Nonetheless, some clinical features of IgG4-RD and iMCD overlap, so differential diagnosis is sometimes difficult, even though the classification and diagnostic criteria of the diseases require careful exclusion of the other. The key findings in IgG4-RD are high IgG4:IgG ratio, allergic features and germinal centre expansion involving T follicular helper cells, while iMCD involves polyclonal antibody production (high IgA and IgM levels), sheet-like mature plasma cell proliferation and inflammatory features driven by IL-6. The distribution of organ involvement also provides important clues in both diseases. Particular attention should be given to differential diagnosis using combined clinical and/or pathological findings, because single features cannot distinguish IgG4-RD from iMCD. In the present review, we discuss the similarities and differences between IgG4-RD and iMCD, as well as how to distinguish the two diseases.

Sasaki T ，Akiyama M ，Kaneko Y ，Takeuchi T ... -  《-》

Comparison of IgG4-Related Lymphadenopathy and Multicentric Castleman's Disease: a Retrospective Study.

Sun C ，Xu G ，Lin J 《Clinical Laboratory》

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

Zhang X ，Zhang P ，Peng L ，Fei Y ，Zhang W ，Feng R ，Zhang W ... -  《-》

Loss of interleukin-21 leads to atrophic germinal centers in multicentric Castleman's disease.

Yajima H ，Yamamoto M ，Shimizu Y ，Sakurai N ，Suzuki C ，Naishiro Y ，Imai K ，Shinomura Y ，Takahashi H ... -  《-》