CD40LG and Mycoplasmoides infection: We describe a case of a 15-year-old boy who presented with an unusual scarlatiniform rash in the setting of a positive Mycoplasma pneumonia IgM but negative anti-streptolysin antibody. While mycoplasma infections with cutaneous manifestations such as scarlatiniform exanthema have been described in textbooks, there are no reports in the primary literature.