An aetiological analysis of erythema nodosum in a community hospital.

Erythema nodosum (EN) is a reaction pattern in the skin characterized by septal panniculitis. Infectious diseases are most common cause of EN. This study was aimed to find out the most common causes for EN as seen in a community hospital over a period of two years. Fifteen patients with EN were subjected to detailed clinical and laboratory investigations to establish the etiology. Immuno - fluorescence and PCR for Mycobacterium tuberculosis were performed in relevant patients. Seven cases were diagnosed to be secondary to tuberculosis that was confirmed by a complete resolution of the lesions after a full course of anti TB chemotherapy. In one patient, the EN was drug induced, two were due to polyarteritis nodosa, one was due to SLE, one was due to streptococcal infection, and three were idiopathic in aetiology. Though the number of patients is small, it still establishes the fact that tuberculosis continues to be the most common cause of EN.