Cutaneous multicentric Castleman's disease mimicking IgG4-related disease.

Castleman's disease, an uncommon lymphoproliferative disorder, can be difficult to differentiate from immunoglobulin (Ig) G4-related disease. The latter is typically characterized by elevated serum IgG4 levels and abundant IgG4-positive cells. However, multicentric Castleman's disease can also have elevated serum IgG4 levels and even fulfill the histological diagnostic criteria for IgG4-related disease. We present a case of cutaneous multicentric Castleman's disease mimicking IgG4-related disease. A 55-year-old Japanese woman developed erythematous and brown plaques on her back. Skin biopsy revealed regressive follicles with interfollicular plasmacytosis, and many plasma cells were positive for IgG4 (mean 263.67±79.19, range 214-355 per high power field). The IgG4-/IgG-positive cell ratios were 35.6%, 36.2%, and 48.4%, respectively, with an average of 40.6%, thus fulfilling the histological diagnostic criteria for IgG4-related disease. Furthermore, serum IgG4 level was significantly elevated (1490 mg/dl; normal range: 4.8-105 mg/dl). However, laboratory findings of anemia, hypoalbuminemia, polyclonal gammaglobulinemia, high C-reactive protein level, and elevated serum interleukin-6 level were consistent with hyper-IL-6 syndrome. Hence, the diagnosis of cutaneous multicentric Castleman's disease was made. In conclusion, IgG4-related disease cannot be differentiated from hyper-IL-6 syndromes on histology alone. Instead, laboratory analyses are necessary to distinguish between the two diseases.

Takeuchi M ，Sato Y ，Takata K ，Kobayashi K ，Ohno K ，Iwaki N ，Orita Y ，Yoshino T ... -  《-》

Multicentric Castleman's disease with abundant IgG4-positive cells: a clinical and pathological analysis of six cases.

Sato Y ，Kojima M ，Takata K ，Morito T ，Mizobuchi K ，Tanaka T ，Inoue D ，Shiomi H ，Iwao H ，Yoshino T ... -  《-》

A case of IgG4-related disease with features of Mikulicz's disease, and retroperitoneal fibrosis and lymphadenopathy mimicking Castleman's disease.

Takenaka K ，Takada K ，Kobayashi D ，Moriguchi M ，Harigai M ，Miyasaka N ... -  《-》

Rheumatoid lymphadenopathy with abundant IgG4(+) plasma cells : a case mimicking IgG4-related disease.

Asano N ，Sato Y 《-》

[IgG4-related disease].

Sato Y ，Yoshino T 《-》