Multicentric Castleman's disease associated with IgA vasculitis (Henoch-Schönlein purpura) responding well to tocilizumab: a case report.

A 41-year-old man was referred to our hospital for the evaluation of hypergammaglobulinemia (IgG 2898 mg/dL and IgA 587 mg/dL), inflammation (CRP 6.7 mg/dL and serum interleukin-6 (IL-6) 15.1 ng/L), and anemia (Hb 10.9 mg/dL). Castleman's disease (CD) was diagnosed by axillary lymph node biopsy. Five months later, painful purpura (multiple palpable 5 mm lesions) developed on his legs, gradually spreading to the upper limbs, thighs, and trunk, accompanied by arthralgia of the wrists, ankles, and knees. Skin biopsy revealed leukocytoclastic vasculitis with IgA deposits in dermal vessels. Accordingly, IgA vasculitis (Henoch-Schönlein purpura) was diagnosed. Tocilizumab (an anti-IL-6 receptor antibody) was administered intravenously at 8 mg/kg and treatment was repeated at monthly intervals. His purpura and clinical findings specific to CD improved rapidly. CD is well known to cause various skin lesions. The findings in this case indicate that overproduction of IL-6 contributes to IgA vasculitis (Henoch-Schönlein purpura) as well as to the pathogenesis of CD.