Synovial complications of spondylepiphyseal dysplasia of late onset.

We describe 2 patients with a late-onset type of spondylepiphyseal dysplasia who developed multiple synovial complications. The synovial manifestations in the first patient included recurrent episodes of acute arthritis due to calcium pyrophosphate dihydrate crystal deposition and, later, chronic synovitis with radiologically evident chondrocalcinosis. In the second patient, cholesterol crystals in synovial fluid, multiple osteochondromata, and a histologic appearance resembling pigmented villonodular synovitis on synovial biopsy were seen. Osteochondromata were identified in 4 other members of this patient's family. Synovial manifestations in the osteochondrodysplasias may be more common than previously recognized.