It is similiar to a Ganglion, both been characterised by a thick fluid content that allows transillumination, the classic diagnostic test. A RC is typically located over the
palmar aspect of the hand, very close to the Metacarpo Phalangeal Joint (MCPJ), near the base of the finger. The nodule is not harmful but can cause pain, especially when gripping. Retinacular cysts can interfere with function. Although approximately 50% of cases do resolve spontaneously, sometimes a patient can’t afford or he is simply unwilling to wait for spontaneous resolution, which will take several months to occurr.
What Causes it?
This is not always clear. Hand injury can predispose to it. Osteoarthritisin the fingers may also increase the risk of developing flexor tendon sheath cysts.
It is essentially clinical. The doctor will ask basic questions, such as:
How long the cyst has been present;
Whether its size has changed;
Whether it is painful and when etc
Palpation will allow assessment of mobility, size and intensity of pain. Shining a light on the cyst (Transillumination) can save you an ultrasound scan, speeding up management.
Occasionally, x-rays, an ultrasound or an MRI scan, may be necessary to clarify the diagnosis.