Primary meningococcal septic arthritis associated with joint calcium oxalate crystals: A case report and review of the literature.

Primary meningococcal septic arthritis (PMSA) is an extremely rare local infection by Neisseria meningitidis in the absence of meningitis or meningococcaemia syndrome. A 30-year-old healthy, immunocompetent man presented with arthralgia, fever, chest rash, and significant swelling of the right knee. On admission, a disseminated maculopapular and purpuric rash, oligoarthritis, neutrophilia, and elevated acute phase reactants were documented. Following arthrocentesis of the right knee, isolation of N. meningitidis and the presence of calcium oxalate crystals in the synovial fluid were reported. The diagnosis of PMSA was made. Histological analysis of the skin lesion showed leucocytoclastic vasculitis. He was treated with intravenous ceftriaxone plus open surgical drainage and ambulatory cefixime with adequate response. After 1 month, he presented resolution of the pathological process. We performed an extensive review of the literature, finding that the key elements supporting the diagnosis of PMSA are prodromal upper respiratory tract symptoms and skin involvement prior to or synchronous with the arthritis. Also, the most frequently involved joint is the knee. This report is the first case of a patient presenting with PMSA associated with calcium oxalate crystals in the synovial fluid. Herein, we discuss the most frequent clinical manifestations, the unusual histological features, the recommended treatment, and the reported prognosis of this rare entity.