Outpouchings of the synovium lining of joints and filled with synovial fluid
Aetiology
The weakness can be developmental (e.g. juvenile Baker’s cyst) or as a result of underlying joint damage/arthritis with buildup of pressure within the joint (adult Baker’s cyst, mucous cyst of DIP joint, wrist ganglion)
Pathophysiology
Not a true cyst as they have no epithelial lining
Histologically - space with myxoid material
Clinical presentation
Occur around a synovial joint or a synovial tendon sheath - commonly arise around the wrist, can also occur in feet and knees
Well-defined round swellings
<10mm - several cm
May be quite firm and readily transilluminate
They are usually painless/non-tender but may feel tight
Skin mobile, fixed to underlying structures
Investigations
Clinical diagnosis
Management
Usually resolve with time but excision may be required for localized discomfort or cosmesis
Needle aspiration may be attempted but recurrance is common
The historic treatment of striking the wrist with a heavy book ('bible technique') to burst the swelling is not advised