{{no footnotes, date=January 2017 Meniscal cyst is a well-defined

cystic A cyst is a closed sac, having a distinct envelope and division compared with the nearby tissue. Hence, it is a cluster of cells that have grouped together to form a sac (like the manner in which water molecules group together to form a bubble); ...

lesion A lesion is any damage or abnormal change in the tissue of an organism, usually caused by disease or trauma. ''Lesion'' is derived from the Latin "injury". Lesions may occur in plants as well as animals. Types There is no designated classif ...

located along the peripheral margin of the

meniscus Meniscus may refer to: *Meniscus (anatomy), crescent-shaped fibrocartilaginous structure that partly divides a joint cavity *Meniscus (liquid) The meniscus (plural: ''menisci'', from the Greek for "crescent") is the curve in the upper surface ...

, a part of the knee, nearly always associated with horizontal meniscal tears.

Signs and symptoms

Pain and swelling or focal mass at the level of the joint. The pain may be related to a meniscal tear or distension of the knee capsule or both. The mass varies in consistency from soft/ fluctuant to hard. Size is variable, and meniscal cysts are known to change in size with knee flexion/extension.

Cause

Various

etiologies Cause, also known as etiology () and aetiology, is the reason or origination of something. The word ''etiology'' is derived from the Greek , ''aitiologia'', "giving a reason for" (, ''aitia'', "cause"; and , ''-logia''). Description In medicine, ...

have been proposed, including

trauma Trauma most often refers to: * Major trauma, in physical medicine, severe physical injury caused by an external source * Psychological trauma, a type of damage to the psyche that occurs as a result of a severely distressing event *Traumatic i ...

hemorrhage Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, v ...

, chronic

infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dis ...

, and mucoid degeneration. The most widely accepted theory describes meniscal cysts resulting from extrusion of synovial fluid through a peripherally extended horizontal meniscal tear, accumulating outside the joint capsule. They arise more commonly from the lateral joint margin, and occur most often in 20- to 40-year-old males.

Diagnosis

Magnetic resonance imaging is the

modality Modality may refer to: Humanities * Modality (theology), the organization and structure of the church, as distinct from sodality or parachurch organizations * Modality (music), in music, the subject concerning certain diatonic scales * Modaliti ...

of choice for diagnosis of meniscal cysts. In their most subtle form, meniscal cysts present as focal areas of high signal intensity within a swollen meniscus. It is not uncommon for

radiologists Radiology ( ) is the medical discipline that uses medical imaging to diagnose diseases and guide their treatment, within the bodies of humans and other animals. It began with radiography (which is why its name has a root referring to radiat ...

to miss this type of meniscal cyst because the signal intensity is not quite as great as fluid on T2 weighted sequences.2 When this fluid is extruded into the adjacent soft tissues, the swollen meniscus subsequently assumes a more normal shape, and the extruded fluid demonstrates a higher T2 signal typical of parameniscal

cysts A cyst is a closed sac, having a distinct envelope and division compared with the nearby tissue. Hence, it is a cluster of cells that have grouped together to form a sac (like the manner in which water molecules group together to form a bubble) ...

. Medial meniscus horizontal tear extending into a meniscal cyst.

Sagittal The sagittal plane (; also known as the longitudinal plane) is an anatomical plane that divides the body into right and left sections. It is perpendicular to the transverse and coronal planes. The plane may be in the center of the body and divi ...

T2 images of a medial meniscus horizontal tear extending into a meniscal cyst. Large medial meniscus cyst.

Treatment

Treatment of meniscal cysts consists of a combination of cyst decompression (

intraarticular A joint or articulation (or articular surface) is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole.Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw- ...

decompression versus open

cystectomy Cystectomy is a medical term for surgical removal of all or part of the urinary bladder. It may also be rarely used to refer to the removal of a cyst. The most common condition warranting removal of the urinary bladder is bladder cancer. Two mai ...

) and

arthroscopic Arthroscopy (also called arthroscopic or keyhole surgery) is a minimally invasive surgical procedure on a joint in which an examination and sometimes treatment of damage is performed using an arthroscope, an endoscope that is inserted into the j ...

repair of any meniscal abnormalities. Success rates are significantly higher when both the cyst and meniscal tear are treated compared to treating only one disease process.

References

Meniscal Cysts
!-- archived URL goes wrong place. Checked June 2020 --> by Rob Gutierrez, M.D. *Campbell, SE, Sanders, TG, Morrison, WB. MR imaging of meniscal cysts: Incidence, location, and clinical significance
AJR 2001;177:409-413
*Helms, CA. The meniscus: Recent advances in MR imaging of the knee
AJR 2002;179(5):1115-1112
Pathology

Signs and symptoms

Cause

Diagnosis

Treatment

See also

References