BAKER CYST (SYNOVIAL CYST) IN OSTEOARTICU LAR TUBERCULOSIS OF THE KNEE-JOINT

A Baker cyst (synovial cyst) in the right knee-joint was demonstrated by ultrasound in a 70-year-old woman with recurrent knee-joint effusio ns after minimal trauma to the knee. Radiological examination in two p lanes showed degenerative changes corresponding to age. Needle punctur e of the knee-joint demonstrated numerous neutrophil granulocytes. As the effusion recurred after one week, despite rest and avoidance of we ight bearing, arthroscopy with removal of the cyst was indicated. But surprisingly histological examination of synovial tissue revealed epit helioid granulomas and Langerhans giant cells. Culture of fluid obtain ed on repeat puncture finally grew Mycobacterium tuberculosis. There w as no evidence of pulmonary tuberculosis. The knee-joint tuberculosis healed completely without residual damage on antituberculosis treatmen t, initially 600 mg rifampicin daily, 300 mg isoniazid daily and 2.5 g pyrazinamide daily for 3 months, followed by rifampicin and isoniazid for a further 6 months.