CD40LG and erythema multiforme: At the baseline, a positive PHOSPHAN reaction for IgM detection with OspC was observed in 13.8% (95% CI: 7.6, 22.5) of patients with EM of <7 days of duration, whereas it was observed in 27.8% (95% CI: 14.1, 45.2) and 31.3% (95% CI: 11.1, 58.7) of patients with EM of 7 to 14 days and >14 days in duration, respectively.