Musculoskeletal #31

8-year-old patient:

– With a chronically painful right knee and ankle

Clinical information:

– Patient with no relevant clinical history
– Parents mention a difficulty when running, the patient trips very easily and sometimes struggles to use the right leg. The right leg is often painful

Showing the X-ray right knee and the pelvis

What do you see?

X-ray right knee

Eccentric, lytic bone lesions with sharp margins
No periosteal reaction
Ground-glass matrix of the lesion in the right tibial diaphysis
Soap-bubbly appearance of the lesion in the femoral diaphysis

X-ray pelvis

Expansile bone lesion with ground glass matrix in the right femoral neck, extending into the proximal diaphysis
Slight varus deformity of the femoral neck
Similar lesion in the right iliac wing/acetabular region

A CT was performed:

Showing X-ray of both feet.

What do you see?

Expansile bone lesion with ground glass matrix involving the 1st metatarsal and proximal and distal phalanges of the left foot
Soap-bubbly lesions of the talus and 5th metatarsal

What is your diagnosis?

Imaging findings:

– Multiple bone lesions with benign appearance
– Expansile lesion with ground-glass matrix in the femoral neck virtually pathognomonic for fibrous dysplasia
– Genetic testing could not reveal mutations of the GNAS gene: no syndromic association in this patient

Teaching points

Teaching points:

Benign bone lesions
– Usually central in bone
– Varying degrees of expansion
– Ground-glass matrix (mildly sclerotic)
– Lack of aggressive features (no periosteal reaction, no cortical breakthrough or soft tissue mass)
Aetiology: developmental dysplasia
Fibrous dysplasia is polyostotic in 15–20%, often in syndromic association (mutations of the GNAS gene)
– McCune-Albright syndrome (in combination with endocrine dysfunctions)
– Mazabraud syndrome

One thought on “Musculoskeletal #31

  1. Lytic bone lesions ( ground glass opacities) with sclerotic margin and deformity of left femoral neck: Poliostotic fibrousdysplasia.

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