[Dorsal mucoid cyst--ganglion-like pseudocyst of the joint space].

A myxoid cyst on the dorsum of the left index finger is presented. A connection of this pseudocyst to the underlying joint was shown by means of magnetic resonance imaging. Surgically the connecting tract to the distal interphalangeal joint was easily demonstrated and histologically a ductal structure was focally seen by means of serial sections. These structures also suggest such a connection. These findings confirm the view that this pseudocyst can be interpreted as a ganglion. Therapeutically complete excision with careful tying off of the channel to the joint appears to be the best method to avoid recurrence. The injection of sclerosing agents, a conservative treatment modality proposed by some authors, may be problematic in the light of the pathogenesis discussed here; however damage to the finger joint has not been so far observed.