1301 camptodactyly-arthropathy-pericarditis (cap) syndrome

Juvenile rheumatoid arthritis (JRA), the most common chronic childhood arthropathy, is a diagnosis of exclusion. We present a congenital syndrome which may be confused with JRA but is distinct on a clinical and histopathologic basis. A 5 year old boy was born with camptodactyly involving the 2nd to 5th digits of both hands. Surgical repair was required at 1 year. Polyarticular swelling, noted at 18 months, progressed to generalized decreased range of motion. X-rays showed only soft tissue swelling and osteoporosis, but no joint space loss or erosions. CBC, ESR, ANA, RF, C3, C4, CH50 and IgG, A, M were normal or negative. An asymptomatic pericardial effusion was detected at 4½ years of age, which progressed despite NSAID therapy. Symptomatic relief eventually required pericardiocentesis. A non-inflammatory fluid was drained. Pericardial biopsy showed minimal inflammation but extensive fibrosis. Synovial fluid from the right knee was noninflammatory. Synovial biopsy showed multiple synovial giant cells (in the absence of a lymphocyte/PMN infiltrate) and extensive deposition of fibrin like material. Camptodactyly with subsequent arthropathy has been reported in multiple members of only 6 families, associated with pericarditis in only 1. This boy's HLA identical sister has no evidence of these manifestations. Camptodactyly beginning in utero may be an earlier and more severe manifestation of the same pathologic process involving joints and pericardium. In summary the CAP syndrome is clinically and histopathologically distinct from JRA. This is the first reported sporadic case of this association.