Baker's cyst in pediatric patients: Ultrasonographic characteristics

Abstract

Objective: Evaluate incidence, etiology, and sonographic features of Baker's cyst in children.

Materials and methods: We examined 16 pediatric patients, with the clinical diagnosis of Baker's cyst. The possibility to confirm or to exclude the presence of the lesion, assess the structure, presence of bilateralism and joint effusion were considered. Three subjects had known juvenile arthritis, 2 hemophilia, 11 a popliteal swelling in the absence of concomitant diseases.

Results: In all patients it was possible to confirm (11) or to exclude (5) the presence of Baker's cyst. The idiopathic forms (6) exhibited anechoic structure; in patients with arthritis (3) there was hypertrophic synovium; in hemophilic patients at the presentation (2) anechoic structure with layering (serum and red blood cells); in chronic hemophilia synovial hypertrophy was seen. Joint effusion was constantly present in children with hemophilia and arthritis and in 1 case of idiopathic cyst.

Conclusion: Baker's cysts in children are rare. Ultrasound is able to confirm or to exclude the presence of the lesion and it is able to evaluate characteristics, bilateralism and association with joint effusion.

Keywords: Arthritis; Baker’s cysts; Children; Juvenile arthritis; Sonography.

Figures

Figure 1

“Idiopathic” Baker’s cyst: axial ultrasound shows anechoic, fluid, mass located between the medial head of gastrocnemius and the semimembranosus tendon (A), intra-articular effusion is also present (B).

Figure 2

Baker’s cysts in child with juvenile arthritis: ultrasonography shows corpuscular fluid lesion (A) associated with corpuscular intra-articular effusion (B).

Figure 3

Baker’s cysts in child with juvenile arthritis: the lesion appears set with corpuscular fluid.

Figure 4

Baker’s cysts in child with juvenile arthritis: ultrasonography shows fluid mass with extensive synovial proliferations.

Figure 5

Baker’s cysts in child with hemophilia: keeping the patient supine for several minutes is possible to distinguish two layers, serum and red blood cell, both in axial (A) that in sagittal (B) plane.

Figure 6

Same case as in Figure 5 after one month: ultrasonography shows synovial hypertrophy linked irritating action of blood on the synovium.