Abstract A 54-year-old woman who had been treated for mixed connective tissue disease for 4 years developed spontaneous rupture of extensor tendons in the wrist. The patient was surgically treated by tendon reconstruction. Histopathological examination of the synovial membrane showed lymphocytic inflammatory cellular infiltration around small blood vessels. The tendon ruptures in this case were most likely caused by synovial membrane proliferation in the wrist and mechanical stress generated by the subluxated distal ulna.
