Differentials
Deep vein thrombosis (DVT)
SIGNS / SYMPTOMS
Patients may have underlying risk factors for development of DVT.
May present with acute calf pain and/or swelling without associated knee pathology.
INVESTIGATIONS
Venous ultrasound will demonstrate thrombus inside the vein.
Popliteal hematoma
SIGNS / SYMPTOMS
Patients may have a history of recent trauma or treatment with anticoagulants.
INVESTIGATIONS
Ultrasound will demonstrate a hematoma in the affected area.
CT and MRI can also identify the hematoma.
Popliteal muscle tear
SIGNS / SYMPTOMS
May cause pain out of proportion localized at the site of the tear.
INVESTIGATIONS
Ultrasound, MRI, and CT will demonstrate the muscle tear.
Knee effusion
SIGNS / SYMPTOMS
May lead to excessive intra-articular fluid in areas other than the cyst location.
INVESTIGATIONS
Ultrasound, MRI, and CT will demonstrate the knee effusion.
Popliteal artery aneurysm
SIGNS / SYMPTOMS
May cause a pulsatile mass in the popliteal fossa.
INVESTIGATIONS
Arterial ultrasound will demonstrate the aneurysm.
Popliteal vein aneurysm
SIGNS / SYMPTOMS
May cause a soft compressible mass in the popliteal fossa.
INVESTIGATIONS
Venous ultrasound will demonstrate popliteal vein aneurysm.
Popliteal soft tissue mass
SIGNS / SYMPTOMS
May cause a palpable firm mass in the popliteal fossa.
INVESTIGATIONS
Ultrasound, MRI, and CT will demonstrate the mass. Sarcoma will have a heterogeneous appearance.
Popliteal lymphocele
SIGNS / SYMPTOMS
Typically a firmer palpable mass than popliteal cyst.
INVESTIGATIONS
Duplex ultrasound demonstrates cyst with clear fluid and acoustic enhancement posteriorly.
Popliteal abscess
SIGNS / SYMPTOMS
May cause a tender, fluctuant collection with erythema in the popliteal fossa.
There may be signs of infection such as fever.
INVESTIGATIONS
Duplex ultrasound or CT scan will demonstrate noncystic, heterogeneous collection.
Popliteal fossa varicosities
SIGNS / SYMPTOMS
There may be visible varicosities in the popliteal fossa.
INVESTIGATIONS
Venous duplex will demonstrate varicosities.
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