Pericruciate meniscal cysts arising from tears of the posterior horn of the medial meniscus: MR imaging features that simulate posterior cruciate ganglion cysts.
OBJECTIVE
The purpose of this study is to describe MR imaging features of an unusual type of meniscal cyst arising from tears of the posterior horn of the medial meniscus in 10 patients.


METHODS
Retrospective review of MR examinations of the knee was performed of 10 patients (nine men, one woman; mean age, 39 years) in whom evidence of a meniscal tear and a cyst-like structure around the posterior cruciate ligament (PCL) was seen.


RESULTS
An oval mass with low signal intensity on T1-weighted MR images and increased signal intensity on T2-weighted MR images posterior to the PCL, simulating a PCL ganglion cyst, was seen in all 10 patients. A tear of the posterior horn of the medial meniscus was also seen in all patients. The sites of communication between the cyst and meniscal tear were observed in sagittal MR images in eight patients. Septation within the cyst and associated joint effusion were seen in eight and four patients, respectively. Arthroscopy in eight patients and transmeniscal needle drainage in the other two patients confirmed both the meniscal tear and the pericruciate meniscal cyst.


CONCLUSIONS
Pericruciate meniscal cysts cause fluid collections posterior to the PCL, simulating a PCL ganglion cyst. Careful analysis of the posterior horn of the medial meniscus should be performed when a cyst-like structure is seen adjacent to the PCL.
Lektrakul
N
N
Department of Radiology, Veterans Affairs Medical Center, University of California, San Diego 92161, USA.
Skaf
A
A
Yeh
L
L
Roger
B
B
Schweitzer
M
M
Blasbalg
R
R
Resnick
D
D
D000293:Adolescent; D000328:Adult; D000368:Aged; D001175:Arthrography; D002357:Cartilage Diseases / Q000175:diagnosis*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods; D008297:Male; D008592:Menisci, Tibial / Q000473:pathology*; D008875:Middle Aged; D016119:Posterior Cruciate Ligament / Q000473:pathology*; D012189:Retrospective Studies; D013581:Synovial Cyst / Q000175:diagnosis*; D000070600:Tibial Meniscus Injuries