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Vascular/Cardiac » Peripheral Vascular
Cystic adventitial disease of the popliteal artery
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Presentation A 32 year old man presents with history of right sided claudication. He has numbness, tingling and decreased distal pulsations of the right lower extremity . He has no history of smoking.
 
 
 
Caption: Sagittal color Doppler of the popliteal artery
Description: The popliteal artery shows normal dimensions. There is an area of soft tissue abnormality along the posterior wall of the popliteal artery and that area is devoid of color. The rest of the popliteal artery shows good wall to wall filling of color.
 
 
 
Caption: Transverse color Doppler of the popliteal artery
Description: The soft tissue mass is noted again in the popliteal artery. This mass shows good posterior enhancement suggesting that this mass is likely to be fluid filled. Incomplete filling of the popliteal artery by color is noted again.
 
 
 
Caption: Sagittal scan of the popliteal artery
Description: The abnormality is demonstrated again in this image.
 
 
 
Caption: Spectral Doppler waveform in the proximal region
Description: A normal arterial waveform with normal flow velocities [peak systolic velocity of 60 cm/sec] is noted in the right distal superficial femoral artery, proximal to the abnormal mass.
 
 
 
Caption: Spectral Doppler waveform in the abnormal region
Description: The peak systolic velocity in the artery is very high in the area of the mass. It is approximately 158 cm/sec.
 
 
 
Caption: MR angiogram image.
Description: The abnormal area shown in the previous ultrasound scans correspond to a cystic structure with fluid signal intensity.
 
 
 
Caption: Axial MR image.
Description: The cyst along the wall of the popliteal artery is noted again.
 
Differential Diagnosis Cystic adventitial disease of the popliteal artery, popliteal artery thrombus.



 
Final Diagnosis Cystic adventitial disease of the popliteal artery.
 
Discussion

Cystic adventitial disease has been described as consisting of a collection of clear gelatinous material within an aberrant synovial type cyst located in the subadventitial plane of the wall of a major artery. These mucoid cysts may cause luminal compromise of the vessel and produce occlusive symptoms. This disease was first described in the external iliac artery in 1947 and in the popliteal artery in 1954.
The popliteal artery is the most common site but the other sites in a descending order of occurrence include –
Ilio-femoral artery, 
Brachial, radial and ulnar artery and
Venous location - popliteal, lesser saphenous vein.

The theories postulated for the etiology of the adventitial cyst include:
1. Developmental theory – all the cysts develop in non-axial [appendicular] vessels. Therefore it is theororized that during limb bud development, mesenchymal cell rests from the adjacent joints migrate into these adjacent vessel walls. Later in life, these cells are responsible for secreting mucoid material resulting in the formation of a cystic mass within the vessel wall.
2. Repeated trauma – microtrauma damages the adventitia, potentiates mucin production which results in the development of the cyst.
3. Synovial origin – as some of these adventitial cysts have shown a communication with the adjacent joint capsule.
4. Ganglionic origin – this has been postulated because the histological appearance and the chemical composition of the adventitial cyst closely resembles that of a ganglion.
Pathologically, the cysts in the vessel wall may be single or multiple; uni or multilocular and range in size from 1-8 cm. The cyst characteristically does not have a lining and does not communicate with the vessel lumen. Its fluid content is rich in hyaluronic acid.

Clinical presentation – The patient is typically a young, non-smoking male who presents with intermittent claudication. The lesion causes dynamic exercise dependent flow inhibition.

Imaging appearance –
Ultrasound with color Doppler shows characteristic features that suggest the diagnosis:
• An anechoic smooth walled mass seen in the wall of the popliteal artery. It shows good posterior enhancement suggesting that it is fluid filled. Sometimes, the contents of the cystic structure appear hypoechoic.
• Usually a single large cyst is seen, which is eccentric in location.
• Reduction in the diameter of the popliteal artery.
• Color Doppler shows the reduction in vessel lumen, increased systolic and diastolic velocities in the narrowed segment of the artery and post stenotic elevations with flow turbulence. There might be distal flow reduction.

The other modalities that can image this disease are CT and MRI, the latter being used more often. T2 weighted MRI images confirm the diagnosis and eliminate the need for conventional angiography. Arteriography shows a smooth-walled curvilinear narrowing.

Differential diagnosis – the following may be considered:
1. Aneurysm – the wall of the popliteal artery aneurysm is much more echogenic than the the wall of the adventitial cyst, if there is an associated thrombus, atherosclerosis or thickened and calcified intima.
2. Synovial cyst- this is seen in the popliteal fossa and causes external compression of the artery.
3. Popliteal artery entrapment syndrome -this occurs due to external compression of the artery as a result of anatomic deviation from its usual course or by compression from musculotendinous structures in the popliteal fossa.
4. Popliteal arterial occlusive disease – in this case, lack of typical risk factors for atherosclerosis makes this diagnosis less likely.

Management- There have been reports of spontaneous regression and spontaneous rupture of the cyst.  However percutaneous US-guided cyst aspiration, surgical cyst evacuation and, if associated thrombosis of the artery, excision of the segment and by-pass graft are some of the treatment options available.

 
Case References 1. Brodmann M, Stark G, et al. Cystic adventitial degeneration of the popliteal artery-the diagnostic value of duplex sonography. Eur J Radiol. 2001 Jun; 38(3):209-12.
2. Wright LB, Matchett WJ, et al. Popliteal artery disease: diagnosis and treatment. Radiographics. 2004 Mar-Apr; 24(2):467-79.
3. Stautner A, Tsounis A, Stiegler H. Cystic adventitial degeneration. An important differential diagnosis in intermittent claudication. Vasa. 2001 May; 30(2):89-95.
4. Levien LJ, Benn CA. Adventitial cystic disease: a unifying hypothesis. J Vasc Surg. 1998 Aug; 28(2):193-205.
5. Lie JT, Jensen PL, Smith RE. Adventitial cystic disease of the lesser saphenous vein. Arch Pathol Lab Med. 1991 Sep; 115(9):946-8.
6. Soots G. Cystic adventitial disease of the popliteal artery. J Mal Vasc. 1990; 15(2):179-81.
7. Hildreth DH. Cystic adventitial disease of the common femoral artery. Am J Surg. 1975 Jul; 130(1):92-96.
 
Follow Up This patient was operated upon and a cyst with one centimeter diameter was found in the mid popliteal artery that extended for a length of 2 cm. A cystotomy of the right popliteal artery was performed. The patient is currently doing well.
 
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