Extensor pollicis longus tenosynovitis mimicking de Quervain's disease because of its course through the first extensor compartment: a report of 2 cases.

We present 2 cases of extensor pollicis longus tenosynovitis caused by the unusual course of the extensor pollicis longus tendon. The extensor pollicis longus tendon passed through the first extensor compartment and was constricted severely. The symptoms were similar to those of de Quervain's disease. The clinical presentation, diagnosis, and surgical technique of this very rare anatomic condition are discussed.