Ganglion cyst is a relatively common entity in the foot and ankle. However, there is considerable overlap in the clinical presentation between ganglion cyst and true neoplasms, both benign and malignant. This learning module will help the clinician separate the two.
Clinical Presentation: Ganglion cyst tends to present in middle age adults, not children. The mass is usually small, 1 to 3 cm. The usual location is near a joint line or along a tendon sheath. The mass may grow and shrink according to the activity level. in some cases, loading or flexing the tendon or joint will make the mass feel noticably more firm.
Clinical exam: A typical ganglion cyst is firm, but somewhat compressible, and usually painless. The cyst will transilluminate with a penlight or a laser pointer. Transillumination is observed in ganglion cysts because the clear fluid in the lesion transmits the light to a larger volume of tissue. An extended area of tissue takes on the color of the light. The room lights may need to be dimmed and the area should be shielded from external light sources to maximize the effect. The surgeon should check a nearby control area to observe how normal tissues glow slightly but do not transilluminate.
Diagnostic procedure: If the lesion fits the above clinical picture, and transillumination is confirmed, aspiration can lead to a conclusive diagnosis and further work-up can be avoided. The diagnosis is confirmed if yellow, non-turbid, slightly viscous fluid were jellylike material is aspirated from the cyst. If the diagnosis is confirmed by aspiration, MRI is unnecessary and treatment may be at the discretion of the doctor. The aspiration may be curative or if the lesion recurs after aspiration, surgical removal can proceed, and further workup is not necessary.
In summary, IF the clinical presentation and exam findings indicate the lesion might be a ganglion, THEN perform transillumination. IF transillumination is positive, THEN perform aspiration. We do not recommend that you aspirate a mass that does not present in the appropriate way and that does not transilluminate.
