Erythema nodosum: an evaluation of 100 cases

In this study, we investigated the clinical features, etiology, and also predictive factors of secondary erythema nodosum (EN) in patients with EN.

A total of 100 patients (mean age: 37 years) diagnosed with EN between 1993 and 2004 in our clinic were included in the study prospectively. A skin biopsy was performed in 46 of the patients. Patients were considered to have secondary EN when an underlying condition was found, and to have primary EN when no such condition was found. For the diagnosis of the underlying diseases, the pertinent diagnostic criteria and/or diagnostic methods were used. Categorical and continuous variables were compared by using chi-square and Mann-Whitney U tests respectively. Multiple regression analysis was applied to the significantly different variables.

The majority of the patients were female (female/male: 6/1) and nearly half (47%) of the cases had a determined etiology. The leading etiology was poststreptococcal (11%), followed in decreasing order by primary tuberculosis (10%), sarcoidosis (10%), Behçet's syndrome (BS) (6%), drugs (5%), inflammatory bowel diseases (IBD) (3%), and pregnancy (2%). Fifteen (15%) patients complained of cough; the diagnosis was primary tuberculosis in eight cases and sarcoidosis in seven. Four patients with arthritis were diagnosed as having BS (in 3) and Crohn's disease (in 1). All the patients were followed for a mean duration of 4.5 years. The nodosities relapsed annually in 62% (33/53) of idiopathic EN patients but in only one (BS) in the secondary EN group. The histology was consistent with EN in all biopsied patients. Our study revealed that fever, leukocytosis, elevated CRP level, accelerated ESR, presence of cough, sore throat, diarrhea, arthritis, and pulmonary pathology were predictors of secondary EN. Recurrence in EN significantly predicted primary EN. All of the patients had bed rest and the majority was given an anti-inflammatory agent (naproxen sodium). The outcomes were usually favorable within 7 days. The patients with an underlying disease were given the specific treatment.

EN has been associated with numerous diseases. In order to reduce cost and duration of diagnosis, every centre should determine its own most frequent etiologic factors. Predictive variables for secondary EN should also be determined and an optimum management for such patients should be clarified. Our study revealed streptococcal pharyngitis, primary tuberculosis, sarcoidosis, IBD, and BS as the main etiologies of EN.