Synovial hemangioma

Synovial hemangiomas are rare benign vascular malformations that occur in relation to the joint. It is sometimes considered a subtype of soft tissue hemangiomas.

Epidemiology

The lesions typically present in children and young adults. Occasionally patients can have recurrent haemarthroses .

Clinical presentation

Patients may have pain, swelling and/or limited joint mobility.

Pathology

The lesions can be cavernous, capillary or mixed.

Location

Most lesions tend to occur around the knee .

Radiographic features

Plain radiograph

Plain film findings are generally non-specific and may be seen as a soft tissue mass adjacent to the knee. Accompanying phleboliths may be present.

MRI

Typically seen as a lobulated intra-articular mass (although the lesions can be either lobulated or diffuse).

Signal characteristics include:

  • T1: usually of intermediate signal
  • T2 
    • markedly hyperintense background; likely from pooled blood within vascular spaces
    • low-signal-intensity linear structures within lesion; likely from fibrous septa or vascular channels
    • fluid-fluid levels may be present 
  • T1 C+: marked enhancement

Differential diagnosis

Imaging differential considerations include: