Streptococcal toxic shock syndrome due to Streptococcus dysgalactiae subsp. equisimilis from retroperitoneal panniculitis during the treatment with anti-IL-6 receptor antibody: A case report.

A 53-year-old man with adult-onset Still's disease developed severe streptococcal toxic shock syndrome (STSS) due to Streptococcus dysgalactiae subsp. equisimilis (SDSE), following retroperitoneal panniculitis. He was receiving tocilizumab (TCZ), an interleukin-6 receptor inhibitor. The modifying effect of TCZ on the immune response and the pathophysiology of SDSE infection may have led to retroperitoneal panniculitis and atypical STSS with delayed shock and flare of soft tissue inflammation.