Myalgia cruris epidemica (benign acute childhood myositis) associated with a Mycoplasma pneumonia infection.

We report the case of a 6-year-old boy who presented with difficulty ambulating and an elevated creatinine phosphokinase level following an upper respiratory tract infection. Crural myositis was diagnosed; convalescent serum was negative for viruses, but demonstrated significant titers to Mycoplasma pneumoniae. Benign acute crural myositis has not heretofore been associated with Mycoplasmal infection.