Unilateral tibia vara in a toddler caused by focal fibrocartilaginous dysplasia

Magnetic resonance imaging of focal fibrocartilaginous dysplasia - findings derived from a three-dimensional gradient echo sequence

BACKGROUND

Focal fibrocartilaginous dysplasia is a rare benign bone lesion of young children that causes deformities in the extremities. However, the pathogenesis and treatments have not been defined and the MR manifestations have been less well described.

OBJECTIVE

To describe the MR manifestations of focal fibrocartilaginous dysplasia, especially on the T1-W three-dimensional (3-D) volumetric interpolated breath-hold examination (VIBE) sequence.

MATERIALS AND METHODS

In this retrospective study, the authors reviewed the MR and radiographic images, pathology and medical records of 21 cases of focal fibrocartilaginous dysplasia. All cases were evaluated by spin-echo MRI sequence. Among them, 17 cases were evaluated by T1-W 3-D VIBE sequence.

RESULTS

The cohort consisted of 13 boys and 8 girls ages 4-75 months. In 14 cases, focal fibrocartilaginous dysplasia was located in the tibia, 3 in the femur and 4 in the ulna. MRI 3-D VIBE sequence findings showed all cases had hypointense fiber band structures in the bone defect areas. The fibrous bands in the lower extremities ended in the epiphysis or epiphyseal plate, and in the upper extremities the epiphysis or carpal bone. Ten cases had hyperintensities that might represent cartilage composition. Four cases had cartilage signals that were continuous with the epiphyseal cartilage. MR spin-echo sequence findings showed that bone marrow edema of the adjacent joint was observed in eight cases, enlargement of the epiphyseal plate in three cases and medial meniscus injury in five cases.

CONCLUSION

The 3-D VIBE sequence reveals useful details in focal fibrocartilaginous dysplasia.

Ulnar focal cortical indentation: a progressive, deforming variant of focal fibrocartilaginous dysplasia

BACKGROUND

Focal fibrocartilaginous dysplasia is a rare growth disturbance of bone resulting in deformity. In the ulna, focal fibrocartilaginous dysplasia is particularly rare, and the characteristic fibroligamentous tether can result in progressive deformity with progressive dislocation of the radial head. The fibroligamentous tether is similar in appearance and function to the Vickers ligament seen in Madelung deformity. The imaging features of ulnar focal fibrocartilaginous dysplasia include a unilateral angular deformity in the ulna with a radiolucent cortical defect and surrounding sclerosis, with secondary radial bowing or radial head dislocation. Focal fibrocartilaginous dysplasia of the ulna has been described using the term ulnar focal cortical indentation.

OBJECTIVE

To review the clinical and radiologic features of four cases of ulnar focal cortical indentation occurring in pediatric patients.

MATERIALS AND METHODS

We retrospectively reviewed picture archiving and communication system and electronic medical record imaging findings with surgical correlation of ulnar focal cortical indentation at two large specialty pediatric hospitals.

RESULTS

Ulnar focal cortical indentation lesions typically arise in the ulnar metaphysis and result in angular forearm deformities with progressive radial deformity including radial head dislocation. Early surgical intervention prevents progression of the deformity and retains range of motion.

CONCLUSION

Ulnar focal cortical indentation, although rare, is likely a progressive form of focal fibrocartilaginous dysplasia resulting in significant deformity and disability. Early recognition of the characteristic imaging features is important for early surgical intervention to preserve range of motion and prevent radial head dislocation.