ABSTRACT: Poncet's disease is a rare syndrome characterized by articular impairment in a form of rare tuberculid. One of the theories of its cause involves an autoimmune response induced by the intravesical administration of the Calmette-Guerin Bacillus or the treatment of bladder carcinoma. Furthermore, there may be an appearance of oligoarticular or polyarticular arthritis, beginning 1-3 months after the start of therapy. Few physicians know the disease and the literature related to that syndrome is scarce and restricted to case reports, which contributes to its under diagnosis.Female patient, 64 years old, Caucasian, in whom was noticed firstly dark urine, without haematuria or dysuria. Later felt also colic pain in the hypogastric region. Microscopically, the conclusive diagnosis was a high grade non-invasive papillary urothelial carcinoma. Thereupon, the treatment of the tumour began with transurethral resection technique and intravesical instillation of Calmette-Guérin Bacillus as adjuvant treatment. Eight months after the beginning of treatment, the lingering presence of the carcinoma was identified. Nevertheless, arthritis was identified through radiographs, after an increase in the clavicle capitation, right knee and left ankle in bone scintigraphy. Coinciding with the joint manifestations, the patient developed fever and purulent urethral discharge (culture was negative). Therefore, trying to investigate the cause of the arthritis, Purified Protein Derivate was taken, with reactive results. An increase of acute phase reactants was found, with other tests resulting normal: blood chemistry, Complete Blood Count, immunology and serology. Human Leukocyte Antigen typing by polymerase chain reaction revealed the presence of A24/AX, B44, B27, BW4/BW4, DQ7 and DQ5. Consequently, Poncet's disease was the diagnostic conclusion. The treatment with intravesical Calmette-Guérin Bacillus was immediately discontinued. The patient received corticosteroids associated with etoricoxib and isoniazid for 4 months, achieving disappearance of the inflammatory joint signs in 3 months. After 6 months, no joint pain recurrence or other manifestations suggesting active disease had been seen.Therefore, such diagnosis should be considered when confronted with an osteoarticular clinical picture in patients treated with intravesical Calmette-Guérin Bacillus, especially patients with HLA-B27 (+) and B7 (+), as Poncet's disease is a reactive arthritis.
