Pseudogout simulating acute suppurative arthritis.

In gout the first attack of arthritis is often acute and most painful. If the affected site is the first metatarso-phalangeal joint the diagnosis presents little difficulty. When larger joints are involved there is a risk that the condition may be mistaken for acute septic arthritis. A more positive approach to the diagnosis has recently been made possible by Seegmiller, Howell and Malawista (1962), who showed that the presence of urate microcrystals within the synovial cavity is the direct cause of acute arthritis. McCarty and Hollander (1961) showed that they can be recognised in synovial fluid by microscopic examination. McCarty, Kohn and Faires (1962), in a study of large numbers of specimens of synovial fluid, found some to contain crystals that were not urate but calcium pyrophosphate. These specimens were obtained from patients suffering from recurrent episodes of more or less acute arthritis, with another feature in common-calcification of joint cartilage. McCarty and Gatter (1964) collected forty such cases and described the clinical features of the condition which they call " pseudogout. " ZitIian and Sit'aj (1963) collected twenty-seven cases showing similar calcification, which they termed " chondrocalcinosis articularis. " Although they failed to detect crystals in the synovial fluid it appears likely that the condition they described is identical with McCarty's " pseudogout. " The subject has recently been reviewed by Bundens, Brighton and Weitzman (1965). In the light ofthese observations it seems that both gout and pseudogout should be regarded as examples of " crystal-induced synovitis. " This represents an important advance in the understanding ofjoint disease and there may be other examples. McCarty and Hogan (1964) suggested that reactions from intra-articular injections of corticosteroids may be caused by this mechanism. During the last eighteen months we have diagnosed pseudogout in six patients. Two presented in the orthopaedic department with arthritis of a large joint sufficiently acute to be diagnosed as septic arthritis. It is therefore important to consider this condition in the differential diagnosis of acute monarticular arthritis. Pseudogout, tending to involve larger joints, may represent a more real source of diagnostic error in this situation than does classical uric acid gout. Previous reports have not emphasised acute septic arthritis in the differential diagnosis ofpseudogout, so we are reporting these two cases to draw attention to this mode of presentation and the steps by which the diagnosis can be established. Case 1-A man of fifty-four complained of …