“…Only 34 cases of primary meningococcal arthritis were reported in the literature from 1980 to 2002 [12] and only sporadically thereafter. For the past 5 years, we found 8 reports of primary meningococcal arthritis in the shoulder, pelvis, sacrolic joint, knee, elbow, ankle, and polyarticular joints, and 2 cases, among those, were sterile or allergic [13][14][15][16][17][18][19][20]. To our knowledge, this is the first report of primary meningococcal arthritis in Japan.…”