CASE 1744 Published on 16.11.2002

Ganglion cyst of the anterior cruciate ligament detected by MRI

Section

Musculoskeletal system

Case Type

Clinical Cases

Authors

A. Cinotti, C. Colacci, P. Campanati, D. Bolognesi.

Patient

50 years, female

Categories

No Area of Interest ; Imaging Technique MR

No Procedure ; No Special Focus ;

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Clinical History

The patient presented with right deep knee pain, exacerbated by squatting and at the limit of flexion. The pain had been present for 5 months, and there was no history of trauma.

Imaging Findings

The patient presented with right deep knee pain, exacerbated by squatting and at the limit of flexion. The pain had been present for 5 months, and there was no history of trauma.

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.

Discussion

Ganglion cysts within the knee are uncommon lesions and arise from the cruciate ligaments or from the infrapatellar fat pad. They are thick-walled cystic spaces of variable size with mixoid matrix. There is no communication between the ganglion cyst and the joint. When arising from the ACL, they tend to be interspersed within its fibres.

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.

Differential Diagnosis List

Intra-articular ganglion cyst of the knee, located between the cruciate ligaments

Final Diagnosis

Intra-articular ganglion cyst of the knee, located between the cruciate ligaments

References

[1] Campanacci M.
Mucous cyst.
In Campanacci M. Bone and Soft Tissue Tumors.
Piccin Nuova Libraria, Padova Springer-Verlag, Wien, New York, pp 1233-7 (1999).

[2] 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)

[3] 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)

[4] 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)

[5] Kang CN, Kim DW, Kim DJ, Kim SJ.
Intra-articular ganglion cysts of the knee.
Arthroscopy 1999 May;15(4):373-8. (PMID: 10355712)

Case information

URL:	https://eurorad.org/case/1744
DOI:	10.1594/EURORAD/CASE.1744
ISSN:	1563-4086

Figure 1

MR imaging of ganglion cyst of the knee

Axial SE T1-weighted image reveals a well-defined cystic mass within the intercondylar notch. The lesion is iso-hypointense to skeletal muscle.

Coronal SE T1-weighted image depicts the extension of the ganglion cyst along the course of the ACL.

Sagittal proton-density-weighted TSE image. Notice that the mass arises from the ACL and changes the appearance of this ligament.

Sagittal GE T2*-weighted image shows the regular course and appearance of the PCL: this means that the ligament is still not affected by the cyst's growth.

Sagittal STIR image: the shaded aspect of the posterior ACL outline may be due to the cyst's tendency to be interspersed within ligament fibres, according to arthroscopy findings.

Figure 2

Arthroscopy of ganglion cyst of the knee