Thymic carcinoma associated with a high serum level of interleukin 6 diagnosed through the evaluation for asymptomatic elevation of acute-phase reactants.

A case of thymic squamous cell carcinoma producing interleukin-6 (IL-6) is reported. C-reactive protein (CRP), white blood cell (WBC) count, and serum IL-6 had been elevated, and normalized immediately after tumorectomy. IL-6 in the culture supernatant from the tumor was significantly elevated and the expression of IL-6 mRNA was demonstrated in the tumor by a reverse transcriptase polymerase chain reaction method. Immunohistochemical study demonstrated that tumor cells were stained positive with an anti-IL-6 antibody. IL-6 derived from the tumor cells reflected the increase CRP and WBC counts. This case suggested that asymptomatic elevation of acute-phase reactants might be clues for the diagnosis of an IL-6 producing tumor.