Complications resulting from misdiagnosing pseudogout as sepsis.
Authors: K Radcliffe, M Pattrick, M Doherty
Journal: BMJ (1986)

Acute pyrophosphate arthropathy (pseudogout) is a common cause ofacute monarthritis in the elderly.As in gout, acute attacks are not Failure to detect calcium pyrophosphate dihydrate uncommonly provoked by surgery or intercurrent illness.' 2 We crystals in elderly patients with acute monarthritis due report on four patients who developed pseudogout in clinical to pseudogout may lead to severe consequences if circumstances which led to initial misdiagnosis as septic arthritis.In prolonged antibiotic treatment is given for presumed each case the correct diagnosis of crystal synovitis was delayed, sepsis permitting development of severe adverse side effects from treatment instituted for sepsis. Case reportsCase I-A 72 year old man with no history of joint disease underwent surgery for a strangulated femoral hernia.On the third postoperative day he developed an acutely painful, swollen left knee and a fever of 38-5°C.On examination the knee was warm and tender with tense effusion and overlying erythema.Aspiration produced 50 ml thin bloodstained fluid with a raised white cell count (58 000/mm3; polymorphs 95%); no organisms were seen on Gram staining and crystals were not specifically sought.Septic arthritis was diagnosed and he was given intravenous flucloxacillin and fusidic acid.Despite negative synovial fluid and blood cultures at 48 hours intravenous treatment was continued.Four days later he developed persistent bloody diarrhoea necessitating intravenous fluid replacement.Reaspiration of his knee then yielded plentiful calcium pyrophosphate dehydrate crystals detected by polarised light microscopy; crystals were also identified on reexamination of the initial aspirate.A radiograph of the knee showed faint fibrocartilage chondrocalcinosis.On sigmoidoscopy an inflamed mucosa but no pseudomembrane was seen.Clostridial toxin was not detected and culture of the stool grew no pathogens.The diarrhoea settled after stopping antibiotics; his knee improved after the second aspiration and was com- pletely normal within five days.Case 2-A 68 year old woman with osteoarthritis of knees, hands, hips, and shoulders underwent left hip replacement.On the third postoperative day she developed painful swelling of the right knee and right wrist and a fever of 39°C.The knee showed a warm, tense effusion with tenderness over the joint line; the wrist was similarly swollen with overlying erythema.Aspiration of the knee produced 60 ml thin, turbid fluid with a raised white cell count (50 000/mm'; polymorphs 90%); 2 ml pus (cell count 68 000/mm'; polymorphs 95%) was obtained from the wrist.Gram staining of both samples gave negative results.She was treated with intravenous flucloxacillin and fusidic acid plus daily aspiration of the knee.Synovial fluid and blood cultures were negative at 48 hours, but her intravenous treatment was continued.Four days later she developed diffuse pruritus and jaundice.Examination of the knee aspirate on the fourth day showed plentiful crystals of calcium pyrophosphate dehydrate (also identified on re-examination of previous aspirates).A radiograph of the knee showed hypertrophic tricom- partmental changes typical ofpyrophosphate arthropathy with faint calcifica- tion in the lateral fibrocartilage.Radiography of the right wrist showed radiocarpal changes typical of pyrophosphate arthropathy but no chondro-