A doença de Poncet é uma condição clínica rara, caracterizada por um acometimento poliarticular em um paciente com diagnóstico de tuberculose, sem evidência de invasão direta do bacilo nas articulações, configurando uma artrite reativa. Documentamos um caso em Porto Alegre: um homem de 56 anos, com evidência de poliartrite aditiva de grandes articulações, investigada há 5 anos, sem diagnóstico definido. Ele havia sido submetido a uma nefrectomia unilateral há 5 anos, e o exame anatomopatológico do órgão revelou tuberculose renal. O teste tuberculínico atual revelou um forte reator (PPD = 20 mm). Análise do líquido sinovial não demonstrou invasão direta do bacilo. Foi instituído tratamento empírico com tuberculostáticos com remissão clínica após 2 meses. Embasados nesses dados, foi feito diagnóstico de doença de Poncet.

Poncet's disease is a rare clinical condition, characterized by polyarticular impairment in a patient diagnosed with tuberculosis, with no evidence of direct bacillary invasion of the joints, constituting reactive arthritis. We report a case of a 56-year old, white male from the city of Porto Alegre, with evidence of additive polyarthritis of the large joints, investigated for five years, and with no defined diagnosis. The patient had undergone unilateral nephrectomy five years before, and the anatomicopathological exam of the specimen revealed renal tuberculosis. The current tuberculin test was strongly reactive (PPD = 20 mm). Analysis of the synovial fluid showed no direct bacillary invasion. Tuberculostatic treatment was initiated and clinical remission occurred after two months. The diagnosis of Poncet's arthritis was established.

The authors report a case of deficiency of the eighth component of complement in a young adult with a history of three episodes of meningitis; one of them proved to be meningococcal. The literature was reviewed and meningitis due to Neisseria meningitidis strains causing disease in complement-deficient and complement-sufficient patients was demonstrated. Meningococcal disease may be the first manifestation of complement deficiency; screening for complement function must be considered for those with invasive meningococcal disease, with posterior evaluation of the components of the terminal pathway of complement.