6b - Answer: 57-year-old male presents with large mass on right knee
History: This 57-year-old male presents with a large mass on his right knee.
MOST LIKELY DIAGNOSIS (that could be life-threatening): Pseudo-pseudothrombophlebitis
Using the diagnostic web viewer, we have provided images that assist in telling our clinical story. Areas of significance are indicated below.
CLINICAL CONSIDERATIONS:
This 57-year-old male presents with a large mass. What is it? But, more importantly, on these axial water-weighted MRI images, what is the potentially life-threatening finding?
The high signal mass is a gastrocnemius semimembranous bursal cyst (one of the many types of Baker’s cysts). The life-threatening finding is the absence of flow phenomena in the popliteal vein. This thrombosis (arrows) can eventually result in a pulmonary embolism. When a Baker’s cyst clinically simulates a popliteal thrombophlebitis, this is called pseudothrombophlebitis. But when it actually coexists with the thrombophlebitis due to compression (as in this case) it is called pseudo-pseudothrombophlebitis.
Case Challenge: Knee MRI Cases
Case Challenge
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Content reviewed: November 3, 2021