Age / Sex : 82 / M

Chief complaint :

Painful Swelling of Lt calf area

1) What is your impression?

Two weeks later, you can see the final diagnosis with a brief discussion of this case.

* Send Application Answers to In Sook Lee, MD ([email protected])

Courtesy : Jeongmi Park, Yeouido St. Mary’s Hospital

Ruptured Baker’s Cyst

Discussion

Findings:

Lateral view of left leg radiograph shows mild soft tissue swelling in posterior aspect of calf without bony abnormality. US shows heterogenous mass-like lesion with internal anechoic portions, suggesting cystic or necrotic portions. Proximal cuts of MRI of the leg represent typical location of the mass which is between gastocnemius medial head and semimembranosus tendon. Peripheral portions of the mass show hyperintense signal on T2-weighted image, intermediate to hypointense signal on T1-wighted image without enhancement, suggesting cystic portions. Central area of the mass show ill-defined hyperintense foci on T1-weighte image without enhancement, suggesting hemorrhage. Posterior compartment of the leg is compressed by this mass-like lesion.

Differential Diagnosis:

Ruptured Baker’s cyst, vascular lesion, lymphocele, abscess, hematoma, soft tissue tumor such as myxoid liposarcoma

Diagnosis:  

Ruptured Baker’s Cyst

Discussion:

Baker’s cyst refers to communication between the posterior knee joint and gastrocneumiosemimembranosus bursa, which includes subgastrocnemius bursa and posterior extended bursa. About half of 50 years old or older persons have Baker’s cyst. Baker’s cyst can extend into proximal part of calf at least 40% of patients. US reveals various echogenicity of the cyst; about 59% anechoic, 23% hypoechoic, 18% mixed echoic nature. Ruptured cyst shows distal tapered end instead if normal round end, which can produce pseudothromobophlebitis syndrome.

References:

1. Torreggiani WC, Al-Ismail K, Munk PL, Roche C, Keogh C, Nicolaou S, et al. The imaging spectrum of Baker's (popliteal) cysts. Clin Radiol 2002;57:681-91.

2. Munk PL, Vellet AD, Levin MF. Leaking Baker's cyst detected by magnetic resonance imaging. Can Assoc Radiol J. Apr 1993;44:125-8.

3. Molpus WM, Shah HR, Nicholas RW, et al. Case report 731. Complicated Baker's cyst. Skeletal Radiol. 1992;21:266-8.