A Tricky Diagnosis of Poncet's Disease.

Erythema nodosum (EN) is a type of panniculitis often benign and self-limited. It may, however, be associated with numerous causes, the most common being infections (namely streptococcal infections), of which tuberculosis (TB) is also one. We report the case of a 43-year-old woman who was referred to our outpatient department with signs of a recurrent EN along with an asymmetrical oligoarthritis of the lower limbs. The investigation excluded all etiological causes of EN, except the interferon gamma release assay (IGRA) which was positive. It was assumed a latent TB infection was the cause of EN. Treatment with isoniazid was started, besides prednisolone and colchicine, with maintained clinical remission. There are just a few cases published about this subject and this intends to emphasize the importance of medical history and of an exhaustive search for a cause, as it may slip away due to the absence of symptoms.