A 54-year-old man, a restaurant waiter, was seen at the orthopedic clinic for a history of pain in his left thumb resulting from a relatively minor trauma sustained at work in September 1990. Past medical history was noncontributory. A radiograph of the left thumb (Fig. 1) was normal. Physical examination revealed mild tenderness around the interphalangeal joint. An initial diagnosis of tenosynovitis of the flexor pollicis longus (FPL) was made. The patient was treated conservatively with mild analgesics (acetylsalicylic acid, acetaminophen) and rest from work. Despite this regimen of treatment, he complained of increasing pain. Local injections of steroids provided only temporary relief. Thirteen months after the initial event, the patient was still unable to work. Exploratory surgery revealed only mild inflammation of the FPL sheath; no bony abnormality was noted. Tenosynovectomy was performed. Pathologic analysis of the surgical specimen showed only scant inflammatory cells of the synovium. Postoperatively, the patient's pain continued to worsen. Two months following surgery, physical examination revealed swelling of the thumb and limitation of movement of the shoulder. The patient was referred to physiotherapy for a shoulderhand syndrome. At this point a 99Tc-MDP bone scan was performed. On blood pool and 2-h images, an area of increased activity was noted around the interphalangeal and metacarpophalangeal joints of the left thumb (Fig. 2). Blood flow was also increased in the left hand as compared with the right. There was no clinical evidence of infection. In September 1992 a control radiograph of the thumb revealed a new abnormality which prompted a second surgical intervention.