This open-label, single center study will provide RoActemra/Actemra (tocilizumab) to a maximum of 4 patients with Multicentric Castelman's Disease who have demonstrated benefit from RoActemra/Actemra in study MRA004US (Chugai Pharma USA) without major toxicities or significant adverse events. Patients will receive their most effective maintenance dose until disease progression or significant toxicity occurs.

Inclusion Criteria:

• Adult patients, >/= 18 years of age
• Evidence of improvement of one or more clinical benefit criteria with acceptable tolerability to RoActemra/Actemra in Protocol MRA001US, maintained clinical benefit in MRA004US, and completion of MRA004US
• Life expectancy > 12 weeks
• Zubrod performance status </= 3

Exclusion Criteria:

• Serious toxicity including anaphylactic reactions to tocilizumab during the MRA004US trial
• Any treatment for Multicentric Castleman's Disease except for corticosteroids within 2 weeks prior to Day 1
• Active infection requiring iv antibiotics for > 1 month and not resolving at least 1 week prior to Day 1; iv antibiotics prophylaxis for infections of implanted venous access portals is allowed
• Active viral infection within 28 days prior to Day 1
• Treatment with any investigational agent other than RoActemra/Actemra within 30 days prior to baseline