Ganglion cysts are by far the most common tumor of the hand comprising 52.6% of all tumors recorded in collective data from three large series totaling 2715 tumors. Ganglions generally occur singly at specific locations but can arise from almost any joint in the hand. They can be associated with bossing of the index and middle carpometacarpal joints, DeQuervain's disease, and Heberden's nodes of the distal interphalangeal joints in elderly patients.

This poster will illustrate the protean manifestations of ganglion cysts with respect to location including the dorsal wrist, volar wrist, volar retinaculum, dorsum of the distal interphalangeal joint (mucous cysts), proximal interphalangeal joint, and intraosseous sites. Lesions initially diagnosed as ganglion cysts include lipomas, anomalous muscles such as the extensor digitorum manus brevis, extensor synovitis, carpal bossing, and giant cell tumors, to name a few.

The extensor digitorum manus brevis is an anomalous muscle that is usually asymptomatic and present since birth. Extensor synovitis usually presents as a soft, non-discrete mass that moves with finger flexion and extension. The osteoarthritic spur of a carpometacarpal boss is not a true ganglion, however, a ganglion is associated with bossing in 30% of cases. This raised, thickened area of bone or exostosis located at the base of the index or middle metacarpal may be confused with a firm dorsal wrist ganglion. Lateral radiographs demonstrate the exostosis. In this poster, we will discuss the incidence of these locations and present several interesting cases illustrating important principles.