Popliteal Swellings
Popliteal swellings are not uncommon. The majority are easily diagnosed on clinical examination alone.
Causes
History
Superficial
Sebaceous cyst
A sebaceous cyst will present as a firm swelling in the skin. It may be tender if it becomes inflamed and there may be a discharge from it.
Lipoma
This presents as a soft lobulated swelling in the subcutaneous tissue.
Varix of the short saphenous vein
This presents as a soft swelling behind the knee, usually associated with varicose veins of the short saphenous system.
Deep
Lipoma
Deeper lipomas are difficult to feel because of the tough overlying fascia. They do not always feel soft and lobulated, as superficial ones do.
Lymphadenopathy
There may be several palpable lumps within the popliteal fossa. The patient will usually draw attention to a lesion distally, either on the leg or on the foot, usually on the lateral margin of the foot or the back of the leg. Other groups of nodes may be enlarged.
Semi-membranosus bursa
The patient complains of a swelling behind the knee that interferes with knee movement, particularly flexion.
