Castleman disease is a rare lymphoproliferative disorder with 2 distinctly 
defined clinical forms. While multicentric Castleman disease (UCD) poses a 
potential therapeutic challenge, unicentric variant has historically been 
considered curable with surgical resection. Hence, little is known to guide 
management of patients with UCD, refractory to surgical resection and 
combination chemotherapy. We present a case of a patient, negative for HIV and 
HHV-8, who had an unsuccessful surgical intervention and no response to 
radiotherapy and chemotherapy. He had severe paraneoplastic pemphigus and was 
treated with tocilizumab, an anti-interleukin-6 receptor monoclonal antibody 
that has demonstrated good response rates in multicentric Castleman disease but 
demonstrated no clinical response despite 2 months of treatment. Our report is 
the first to describe a lack of response to tocilizumab in the rare setting of 
refractory UCD and discuss potential for distinct disease biology.