A case of Poncet's disease (tuberculous rheumatism).

We describe a 37-year-old woman with recurrent polyarthritis, and recurrent erythema nodosum on the flexible side of her left forearm. On an X-ray of the chest, infiltration of the right upper lobe was observed. Transcription-reverse transcription concerted reaction in sputum samples revealed Mycobacterium tuberculosis (M. tuberculosis). Resolution of the polyarthritis with anti-tuberculosis (TB) drugs occurred in 3 days. We diagnosed her with Poncet's disease (PD). PD is considered to be a reactive arthritis, which is a different entity from tuberculous arthritis. Although PD is a rare disease, we should be aware of it as one of the differential diagnoses, even in patients without typical symptoms of TB.