Radiographic findings were negative. MR imaging showed a well-defined ovoid cystic mass, located in the intercondylar notch, associated with the anterior cruciate ligament (ACL). The cyst extended along the course of the ACL and markedly changed the appearance of the ligament. The lesion was solitary, with a diameter of 3cm.
The patient underwent arthroscopy for excision of the cyst and articular debridement. The histological data confirmed the MRI diagnosis of a ganglion cyst of the knee.
The MRI study was performed using an MR scanner (0.2T) with a dedicated coil. The examination consisted of T1-weighted spin-echo (SE), PD-weighted turbo-spin-echo (TSE), T2*-weighted gradient-echo (GE) and GE-STIR sequences, performed in the axial, sagittal and coronal planes.
Symptoms are related to the size and the location of the cyst within the knee joint, and may be absent. The patient may complain of pain and limitation in the range of motion up to a complete articular lock.
Pathogenesis is related to mechanical stresses and to a hyperplastic-degenerative phenomenon, caused by exuberant reactive fibroblastic proliferation with overproduction of mucin.
Intra-articular ganglion cysts of the knee have a distinctive MR appearance: homogeneous high signal intensity in relation to muscle on T2*-weighted GE and GE-STIR sequences, and hypo- or isointense on T1-weighted SE and PD-weighted TSE sequences.
Lesions located in the intercondylar notch are usually diagnosed by intimate association with the cruciate ligaments, while lesions arising from the infrapatellar fat pad must be differentiated from synovial haemangioma and synovial sarcoma.
Local recurrences are infrequent and are related to repetition of the pathogenetic event. Treatment depends on dimensions and symptoms: injections of corticosteroids for smaller cysts, excision for larger and symptomatic lesions.
In Campanacci M. Bone and Soft Tissue Tumors.
Piccin Nuova Libraria, Padova Springer-Verlag, Wien, New York, pp 1233-7 (1999).
Narvကez JA, Narvကez J, Aguilera C, De Lama E, Portabella F.
MR imaging of synovial tumors and tumor-like lesions.
Eur Radiol. 2001;11(12):2549-60. (PMID: 11734958)
Kim MG, Kim BH, Choi J-A, Lee NJ, Chung KB, Choi YS, Cho SB, Lim HC.
Intra-articular ganglion cysts of the knee: clinical and MR imaging features.
Eur Radiol. 2001;11(5):834-40. (PMID: 11372618)
Recht MP, Applegate G, Kaplan P, Dussault R, Schweitzer M, Dalinka MK, Resnick D.
The MR appearance of cruciate ganglion cysts: a report of 16 cases.
Skeletal Radiol. 1994 Nov;23(8):597-600. (PMID: 7886467)
Kang CN, Kim DW, Kim DJ, Kim SJ.
Intra-articular ganglion cysts of the knee.
Arthroscopy 1999 May;15(4):373-8. (PMID: 10355712)