title: Gas-like radiolucencies in a popliteal cyst.
abstract: A 71-year-old man with rheumatoid arthritis complained of pain and swelling in the left calf. X-ray examination of the calf disclosed radiolucencies suggestive of soft tissue gas; however, subsequent investigation revealed no evidence of infection and an arthrogram showed a dissected popliteal cyst in the area of the gas. Gas-like radiolucencies in a popliteal cyst are an unusual finding which has not been previously reported.
mesh_terms: D000368:Aged; D001172:Arthritis, Rheumatoid / Q000150:complications*; D003560:Cysts / Q000150:complications / Q000000981:diagnostic imaging*; D003937:Diagnosis, Differential; D004618:Embolism, Air / Q000000981:diagnostic imaging* / Q000209:etiology; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging*; D007866:Leg / Q000098:blood supply; D008297:Male; D011859:Radiography; D013924:Thrombophlebitis / Q000000981:diagnostic imaging