Primary tuberculosis cases presenting with erythema nodosum.

Erythema nodosum (EN) is seen only in the primary tuberculosis (TB) form of tuberculous diseases. Among the etiologies of EN, TB is the most frequent disorder in developing countries. We aimed to assess our patients with EN in reference to primary TB. We evaluated 335 patients with the diagnosis of TB during last 20 years; retrospectively 61 (18%) of these cases had pulmonary and 274 (82%) had extrapulmonary TB. Ten (16%) of the pulmonary TB cases were primary. All 10 patients with primary TB presented with EN. Among 50 patients with EN diagnosed and followed during the last 10 years, the etiology was determined in 56%, and primary TB was the most frequent: 20%.