Presentation
Swelling of the left knee for six months with recurrent atraumatic painful bloody knee effusions.
Patient Data
There are small calcifications with regular margins in the soft tissues of the medial compartment of the knee. Obliterated the suprapatellar recess.
MRI scan showed a well-defined mass located within the suprapatellar pouch, but infiltrating the vastus medialis muscle and Hoffa fat pad. The mass appeared lobulated in contour with internal septae. There are some phleboliths inside the blood vessels and areas of thrombosis with increased signal on T1 images. T1-weighted post-enhanced images show inhomogeneous contrast enhancement of the mass.
Case Discussion
Synovial hemangioma is a rare benign vascular malformation that occurs in relation to the joint. The lesions typically present in children and young adults. Plain films are often of poor diagnostic but sometimes they show soft tissue density, suggesting joint effusion or a mass. They may contain phleboliths or amorphous calcifications. Hemangiomas may cause skeletal hypertrophy or remodeling.