A Study to Evaluate the Safety of Long-term Treatment With Siltuximab in Patients With Multicentric Castleman's Disease

Inclusion Criteria: * Has multicentric Castleman's disease * Have previously been enrolled in Study C0328T03 or CNTO328MCD2001 (either treatment arm) * Have had their last administration of study treatment (siltuximab or placebo) less than 6 weeks (window of plus 2 weeks) prior to first dose * Patients must not have had disease progression while receiving siltuximab. For those patients originally assigned to placebo in the CNTO328MCD2001 study, patients who have received less than 4 months of siltuximab following crossover will also be eligible * Have adequate clinical laboratory parameters within 2 weeks prior to the first dose of siltuximab for this study Exclusion Criteria: * Unmanageable toxicity, an adverse event, progression of disease, or withdrawal of consent as reason for discontinuing treatment from previous sponsor-initiated siltuximab study * Vaccination with live, attenuated vaccines within 4 weeks of first dose of this study * Known unmanageable allergies, hypersensitivity, intolerance to monoclonal antibodies, to murine, chimeric, human proteins or their excipients