A 38-year old man is referred to a vascular clinic due to a 3-month history of left calf pain after walking about two blocks. Over the counter nonsteroidal anti-inflammatory drugs (NSAIDs) and common analgesics do not relieve his symptoms. He is a nonsmoker and his medical history includes dyslipidemia and a surgery for left anterior cruciate ligament rupture 10 years ago. He has no family history of cardiac disease. Laboratory workup, except for an LDL-C value of 145 mg/dl, is completely normal. Physical examination reveals palpable distal pulses to the left and right lower extremity, however distal pulses to the left foot are decreased with ipsilateral knee flexion. Right and left ankle-brachial index (ABI) values at rest are 1.3 and 1.2 respectively. A magnetic resonance imaging (MRI) is ordered and reveals small round masses in the arterial wall of the popliteal artery.
What is the most likely diagnosis in this patient?
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The correct answer is: B. Adventitial cystic disease of popliteal artery
Popliteal artery stenosis manifests primarily with intermittent claudication in elderly patients and is associated with systemic atherosclerosis.1,2 Other causes of popliteal artery occlusive disease include popliteal artery aneurysm, popliteal entrapment syndrome and cystic adventitial disease. Diminished distal pulses with ipsilateral knee flexion suggests that this patient suffers from adventitial cystic disease.3
Adventitial cystic disease of popliteal artery is an extremely rare cause of popliteal artery occlusion mostly found in middle aged men with no cardiovascular risk factors.1,2 Mucinous cysts form within the adventitia of the popliteal artery and in some cases can cause acute limb ischemia due to complete occlusion of the vessel. The clinical feature that distinguishes this disease from other possible causes of popliteal artery occlusion is the loss of palpable foot pulses with knee flexion (Ishizawa sign).3 MRI usually reveals concentric ovoid masses that lead to hourglass stenosis.1,2 Open surgical intervention with cyst resection represents the most common treatment approach for the disease.1
Popliteal artery entrapment syndrome (Answer A) results from an anomalous relationship between the popliteal artery and myofascial structures of the popliteal fossa. On physical examination, foot pulses are diminished after passive dorsiflexion of the foot. It primarily affects healthy young-adults and commonly presents as calf pain among male athletes.4
Systemic distal embolization (Answer B) occurs in the setting of atrial fibrillation or any cardiovascular disease that predisposes to thrombus formation and subsequent distal embolization. This patient does not have any history of a disease that might have contributed to his symptoms.
Atherosclerosis (Answer D) and popliteal artery aneurysm (Answer E) are common causes of popliteal artery occlusion in elderly patients (i.e. 6th-7th decade of life), who suffer from contemporary cardiovascular comorbidities. Acute thrombosis of the popliteal artery presents with acute limb ischemia and warrants immediate revascularization for limb salvage. Physical examination of this patient does not indicate limb threatening ischemia.
Educational objective
Adventitial cystic disease of the popliteal artery represents an uncommon cause of popliteal artery occlusive disease occurring mainly in healthy young males.1 Mucinous cystic lesions are formed within the adventitia of the vessel's wall, narrowing the lumen of the popliteal artery and as such diminishing blood flow to lower limb. Symptoms of ischemia are present during exercise when the demand for oxygen supply to lower foot is higher. Not palpable pulses at the posterior pedal artery, while the knee is flexed, is indicative for the disease.3
References
Desy NM, Spinner RJ. The etiology and management of cystic adventitial disease. J Vasc Surg 2014;60:235-45.
Kawarai S-I, Fukasawa M, Kawahara Y. Adventitial cystic disease of the popliteal artery. Ann Vasc Dis 2012;5:190-93.
Wick MC, Tauscher T, Rieger M. Claudication due to cystic adventitial degeneration: a classical differential diagnosis of atherosclerotic peripheral artery disease. Circulation 2012;125:1926-27.
Carneiro Júnior FCF, Carrijo ENDA, Araújo ST, Nakano LCU, de Amorim JE, Cacione DG. Popliteal artery entrapment syndrome: a case report and review of the literature. Am J Case Rep 2018;19:29-34.
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