Meniscal cyst 2481120 220833083 2008-06-21T20:45:07Z ThomDoughty 5796777 /* Etiology */ 85% of meniscal cysts occur laterally. {{Orphan|date=November 2006}} A '''meniscal cyst''' is a well-defined [[cystic]] [[lesion]] located along the [[peripheral]] margin of the [[meniscus]], a part of the knee, nearly always associated with horizontal [[meniscal tears]]. ==Etiology== Various [[etiology|etiologies]] have been proposed, including [[Physical trauma|trauma]], [[hemorrhage]], chronic [[infection]], and [[mucus|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. ==Signs/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/[[fluctuan]]t to hard. Size is variable, and meniscal cysts are known to change in size with knee flexion/extension. ==Radiologic Findings== [[Magnetic resonance imaging]] is the [[modality]] 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]] 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 relatively higher T2 signal typical of [[parameniscal]] [[cysts]]. Medial meniscus horizontal tear extending into a meniscal cyst. [[Sagittal]] 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]] decompression versus open [[cystectomy]]) and [[arthroscopic]] 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== *[http://uwmsk.org/moodle/mod/resource/view.php?id=397 Meniscal Cysts] by Rob Gutierrez, M.D. *Campbell, SE, Sanders, TG, Morrison, WB. MR imaging of meniscal cysts: Incidence, location, and clinical significance. [http://www.ajronline.org/cgi/content/full/177/2/409 AJR 2001;177:409-413]. *Helms, CA. The meniscus: Recent advances in MR imaging of the knee. [http://www.ajronline.org/cgi/content/full/179/5/1115 AJR 2002;179(5):1115-1112]. [[Category:Pathology]]