Background: Erythema nodosum (EN) is associated with many infectious diseases. The purpose of this study was to evaluate the relative prevalence of associated diseases in a large series of EN, and to review the previously described causes of EN.
Materials and methods: A total of 157 inpatients with a diagnosis of EN made in Strasbourg, France between 1960 and 1995 were studied retrospectively, but only 129 patients with confirmed EN were evaluated. A biopsy was taken in 30 patients with atypical clinical symptoms. Chest radiography, blood cell count, throat swab, and anti-streptolysin dosage were performed systematically. Viral investigations and serodiagnoses for various bacterial infections were carried out in approximately half of the patients. All investigations were analyzed retrospectively and compared with the world literature.
Results: The female: male ratio was 5 : 1 and the mean age was 31 years. We found 28% confirmed streptococcal infections, 11% sarcoidosis, 1.5% enteropathies, 1.5% Chlamydia infections, 0.8% Mycoplasma infections, 0.8% Yersinia infections, 0.8% hepatitis B, and 0.8% tuberculosis (one case). The causative factor could not be determined in 55% of patients.
Conclusions: Our data confirm the predominance of streptococcal infections and sarcoidosis among patients with EN. Tuberculosis has virtually disappeared, since the last case was observed in 1962. Various viral or bacterial diseases are rarely associated with EN, but all patients were not thoroughly investigated. A large and prospective study should be performed in order to determine the true prevalence of associated diseases in EN. In the absence of specific symptoms, exhaustive investigations are not cost-effective.