Long-term follow-up of erythema nodosum.

One hundred and fifty-four patients with erythema nodosum who attended the skin clinic at Ramathibodi Hospital from January 1990 to December 2000 were evaluated retrospectively with regard to the etiology of erythema nodosum. Of 49 patients who attended the skin clinic during that time 26 returned for reevaluation. Of the 154 patients, their ages ranged from 10-72 years old; 138 were females, 16 were males. The most common cause of erythema nodosum was tuberculosis (12.3%). Upper respiratory tract infection was found in 3.9 per cent. Other causes included Behcet's disease, sytemic lupus erythematous, drugs, pregnancy, chronic myeloid leukemia, leprosy, Reiter's syndrome and inflammatory bowel disease. Of the 26 patients who returned for reevaluation, pulmonary tuberculosis was identified in only one patient who had developed erythema nodosum 16 months earlier. In conclusion, it was found that tuberculosis is still a predominant cause of erythema nodosum among Thai patients.