Clinical and biological characteristics of immunopathological disease-related erythema nodosum in children

We report a series of 22 children with idiopathic, drug unrelated erythema nodosum (EN) admitted to our Department. In 5 of them an history of strepto coccal pharyngitis was referred; the remaining patients came to us with a d iagnosis of "EN Of unknown origin". Acute phase reactants, immunoglobulins, stool alpha 1 antitrypsin, ANA, anti dsDNA antibodies and ANCA assay, ches t roentgenogram, tuberculin test, and ophthalmologic assessment were perfor med in all patients. Etiologic diagnosis was made in 16 patients: Streptoco ccal pharyngitis (5 cases), chronic inflammatory bowel disease, IBD (3 case s), Behcet syndrome (2 cases), Yersinia enteritis (2 cases), infectious mon onucleosis, atypical mycobacterial infection, immunodeficiency related infe ction, and SLE-like syndrome due to C4 deficiency (1 case each). We found o ral/scrotal aphthae in 3 cases, gastrointestinal symptoms in 5 cases, arthr itis in 3 cases. Acute phase reactants were positive in 16 patients without correlation to the underlying disease. Conversely, the increased alpha 1 a ntitrypsin stool excretion and IgA serum concentration seemed to represent helpful indicators of IBD and Behcet syndrome, respectively. Proinflammatory cytokine pattern showed increased IL6 serum concentrations both in infectious and in non infectious disease-related EN, whereas a mino r involvement of TNF was found in these patients.