Radiological Mimics of Popliteal Cysts: An Algorithmic Approach Using US and MRI to Identify the Potentially Malignant Lesions: Case Series

Background: Popliteal cysts are common and present as asymptomatic lumps in the medial popliteal fossa. Some have complex internal characteristics such as septa and loose-bodies. However, not all are popliteal cysts and can be aggressive. These lesions need to be differentiated by the absence of the communicating neck with the joint on ultrasound. Presence of Doppler flow of non-communicating cysts requires further evaluation on MRI, prior to performing a biopsy. Using a case series, we propose an algorithmic approach that is simple and will help identify the malignant lesions and institute appropriate management. Case-Presentation: Popliteal Cyst: On ultrasound: characteristic neck communicating with knee joint. Synovial Sarcoma: Gadolinium enhancement, with areas of low-, iso- and hyper-intense signal to fat on T2. Synovial-Osteochondromatosis: Non-mineralized: T1-low/intermediate intensity;T2-high intensity. Mineralized type: low intensity on T1 & T2. Thrombosed Popliteal Aneurysm: Lamellated appearance-high/low signal intensity on T2. Myxoid-Liposarcomas: Inhomogeneous appearance;homogenous with gadolinium. Usually require a biopsy for diagnosis. Conclusion: The cystic lesions in the medial aspect of the popliteal fossa can be misdiagnosed. Our article reiterates the importance of the communicating neck that separates popliteal cysts from other mimics. We have proposed an algorithm to identify these mimics.

Efficacy of Ultrasound-Guided Unidirectional Valve Enlargement in Treatment of Popliteal Cysts

Purpose: To investigate the effect of ultrasound-guided unidirectional valve cleft enlargement in the treatment of popliteal cysts. Methods: Forty-eight patients with popliteal cysts who met the inclusion criteria and were admitted to our hospital from December 2018 to June 2020 were randomly divided into group A (24 cases) and group B (24 cases). Group A was treated with a central venous catheter dilator, and group B was treated with traditional open surgery to remove the popliteal cyst. Visual analogue scale (VAS) was used to evaluate discomfort. The VAS, Lysholm score of knee joint and Rauschning-Lindgren grade 0~I improvement rate were compared at 6 months after operation. Results: The postoperative VAS in group A was significantly better than that in group B (P < 0.05), and the postoperative Lysholm score and Rauschning-Lindgren grade 0~I in group A were higher than those in group B (P < 0.05). There was no recurrence or other complications in either group. Conclusions: Ultrasound-guided central venous catheter dilator is more effective than traditional surgical resection of popliteal cysts.

Treatment of Popliteal Cyst through Radiofrequency Thermocoagulation under Ultrasound Guidance

Objective: The purpose of this study was to explore the clinical efficacy and security of the treatment of popliteal cyst through radiofrequency thermocoagulation (RFT) under ultrasound guidance. Methods: The clinical data of 35 patients with popliteal cyst, who were treated by RFT under ultrasound guidance from June 2019 to June 2020, were retrospectively analyzed. The Visual Analogue Scores (VAS) and the size of cyst before and after treatment were recorded at the first month, the third month, the sixth month. After six months, the recovery rate of Rauschning and Lindgren classification (R-L classification) level 0, 0 - I were counted. All the complications of the patients were observed. Results: 32 patients were followed up for six months. The scores and cyst sizes of each patient before and after the treatment were on a normal distribution curve. There was no significant difference in VAS scores before and after the treatment (P > 0.05). However, there was a significant difference in cyst sizes before and after the treatment (P < 0.05). Moreover, there was no significant difference in VAS scores and cyst sizes in each period after treatment (P > 0.05). According to the R-L classification in 6 months after treatment: the recovery rate of class 0 was 62.5% and class 0 - I level was 87.5%. There were no serious complications in the process. Conclusion: Treatment of popliteal cyst through RFT under ultrasound guidance is a simple, easy, reliable method that is worthy of clinical promotion.