Atypical erythema nodosum in atypical tuberculosis presentation.

Erythema nodosum (EN) is an inflammatory disease of the skin and subcutaneous tissue that may be found in association with many systemic diseases such as infectious diseases, sarcoidosis, Behçet disease, inflammatory bowel diseases and tumours, in particular lymphoma. EN may be also induced by some drugs, including mainly estroprogestinics, salicylic acid, minocycline and sulfamidic acid. Due to the numerous possible causes, sometimes it may be very difficult to achieve a correct diagnostic interpretation, especially when an isolated EN represents the revealing feature, as in the following case. We describe the case of a patient, of young age and good clinical condition, who developed EN during the course of abdominal tuberculosis. The diagnosis was obtained by histologic examination of the abdominal formation since positron emission tomography and total body axial tomography were not useful in discriminating EN from malignancies.