MR Imaging of Cysts, Ganglia, and Bursae About the Knee
Section snippets
Synovial cyst
The definition of a synovial cyst is a juxta-articular fluid collection that is lined by synovial cells. It is this synovial lining that histologically distinguishes them from other juxta-articular fluid collections. A synovial cyst represents a focal extension of joint fluid that may, or may not, communicate with the joint, and may extend in any direction [1], [2]. The prototypical example of a synovial cyst is the popliteal cyst.
Ganglion
A ganglion is a cystic, tumor-like lesion of unknown origin, which is surrounded by dense connective tissue filled with gelatinous fluid rich in hyaluronic acid and other mucopolysaccharides [31]. These cysts are classified as myxoid lesions, with suggested causes including synovial herniation and tissue degeneration or repeated trauma [32], [33], [34]. The World Health Organization does not address ganglia because they are not tumors, and, therefore, no rigid classification scheme exists. The
Subchondral cyst (geode)
Subchondral lucencies are referred to by many names in the literature, including subchondral cysts, synovial cysts, subarticular pseudocysts, necrotic pseudocysts, and geodes [48]. The term subchondral cyst is not accurate technically because the cyst does not have an epithelial lining and is not fluid filled uniformly [48]. However, this term is ubiquitous in the literature, and will therefore be used in the following discussion.
OA is a process of articular degeneration characterized by
Meniscal cyst
A meniscal cyst is a focal collection of synovial fluid located within, or adjacent to, the meniscus. Various theories have been proposed regarding the etiology of these cysts, with the most widely accepted reason stating that joint fluid accumulates within a torn or degenerated meniscus, creating an intrameniscal cyst, and fluid extravasation through a meniscal tear into the surrounding soft tissues results in parameniscal cyst formation [30], [51], [52]. A horizontal component to the tear is
Bursa
Bursae are normally occurring, synovial-lined structures that function to reduce friction between moving structures, such as tendons, ligaments, and bone. Typically, they are not visible on imaging because they normally contain only limited fluid. Inflammation from local and systemic processes such as overuse, trauma, internal joint derangement, inflammatory arthropathy, and collagen vascular diseases, in addition to infection and hemorrhage, may cause thickening of the synovial lining and
Summary
Cystic lesions about the knee are common findings, representing diverse causes and, therefore, varied prognosis and therapeutic options. MR aids in the characterization of lesions by first localizing them, and then defining their relationship with adjacent structures and identifying any additional abnormalities. Cystic lesions and their relationships are best depicted on long TE/TR (fluid-sensitive) MR sequences. Careful attention to these details will allow one to provide a reasonable MR
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Comment on “The potential pitfalls of synovial sarcoma mimicking intraneural ganglion cyst: A case report and literature review”
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2023, Asian Journal of SurgeryMR Imaging of the Knee Bursae and Bursal Pathology
2022, Magnetic Resonance Imaging Clinics of North AmericaCitation Excerpt :In many cases, bursitis may be reactive to an injury involving an adjacent structure, such as a ligament or tendon. When the bursa is primarily affected, the most common causes include acute or repetitive trauma, chronic overuse, infection, and inflammatory arthropathy.1–3,7,28 Chronic repetitive trauma is the most common cause of anterior knee bursitis, classically described in patients with history of occupational kneeling, such as housemaid's knee (prepatellar bursitis) or clergyman's knee (superficial infrapatellar bursitis).28,34
Ganglion cyst at the proximal tibiofibular joint - A rare cause of compression neuropathy of the peroneal nerve
2022, Radiology Case ReportsBone Tumors Occurring in the Soft Tissues: A Review of the Clinical, Imaging, and Histopathologic Findings
2021, Current Problems in Diagnostic RadiologyCitation Excerpt :MR imaging of SC demonstrate a well-defined cystic mass which is T1 hypointense and T2 hyperintense. Both may demonstrate variable internal signal depending on the presence of hemorrhage or debris, and in the case of SC, chondral/osseous bodies.52,53 Infection of SC may also lead to wall thickening and heterogenous wall/septal enhancement.52,54
Radiographic/MR Imaging Correlation of Soft Tissues
2019, Magnetic Resonance Imaging Clinics of North AmericaCitation Excerpt :If large enough, they may be suspected on plain films if a nonspecific soft tissue swelling is seen adjacent to the joint (Fig. 21). Peritrochanteric, subacromial-subdeltoid, ischiogluteal, pes anserine, iliopsoas, pre- and infrapatellar, and retrocalcaneal and olecranon bursae are most commonly involved.69–75 An adventitious bursa results from inflammation and fibrinoid necrosis of connective tissue in areas subject to chronic frictional irritation.
This article was originally published in Magnetic Resonance Imaging Clinics of North America 15:1, February 2007.