Acute de Quervain's Tenosynovitis Caused by Calcium Pyrophosphate Dihydrate Deposition.

A patient presented with acute de Quervain's tenosynovitis with no history of trauma or overuse. Infection was ruled out. Aspiration of the involved tendon sheath yielded a significant quantity of tenosynovial fluid closely resembling viscous synovial fluid, which showed intracellular calcium pyrophosphate dihydrate crystals. X-rays showed flecks of linear calcification in the region of the tendon sheath. This is a rare clinical presentation of calcium pyrophosphate dihydrate disease.