Mycoplasma pneumoniae as a trigger for Henoch-Schönlein purpura in children.

Mycoplasma pneumoniae is one of the most common causes of respiratory tract infections in children. Extrapulmonary manifestations are seen in up to 25% of infected patients. Extrapulmonary complications are associated with the central nervous system, gastrointestinal tract, skin changes, myocarditis, pericarditis, hemolytic anemia, thrombocytopenia and thrombosis. The majority of extrapulmonary symptoms are associated with skin changes such as exanthematous skin eruptions, erythema nodosum, urticaria, Stevens-Jonson syndrome. M. pneumoniae stimulates production of the interleukins and tumor necrosis factor (TNF) α and can cause vasculitis. Henoch-Schönlein purpura (HSP) is a leucoclastic vasculitis that affects small vessels. Clinical manifestations of HSP include typical rash, arthritis, gastrointestinal and sometimes renal involvement. The main feature in HSP is abnormal IgA deposits in vessel walls. Circulating abnormal glycosylated IgA 1 and IgG antibodies form immune complexes: IgA1-IgG and anti-IgA 1. Immune complexes activate cytokines, parts of complement and influence directly the endothelium. We report cases of three children with Henoch-Schönlein purpura with prolonged and recurrent skin and joint changes. The serological analysis (positive serum IgM) confirmed Mycoplasma pneumoniae infection. Treatment with clarithromycin caused complete regression of disease. We suggest that in the case of prolonged symptoms of vasculitis due to Henoch-Schönlein purpura, Mycoplasma pneumonia infection may be a potential cause of exacerbation of the disease.