CASE 66

By: Dr. Amna Kashgari MD,SSC-Rad

HISTORY: A 14-year-old boy with limping and chronic left hip pain.

What are your findings?

What is your differential diagnosis?

What is your most likely diagnosis?

What is  McCune-Albright syndrome?

FINDINGS:

Frontal X-ray of the pelvis shows an expansion of the proximal femur with ground glass lesions involving the meta-diaphysis interspersed with sclerotic narrow zone of transition and a shepherd's crook deformity.

DIFFERNTIAL DIAGNOSIS:

• Fibrous dysplasia.

• Enchondromatosis.

• Aneurysmal bone cyst.

• Osteofibrous dysplasia (only in Tibia).

• Adamantinoma.

DIAGNOSIS:

Fibrous dysplasia.

McCune-Albright syndrome: It is a triad of polyostotic fibrous dysplasia, café-au-lait macules, and endocrine dysfunction.

PEARLS AND DISCUSSION:

Fibrous dysplasia is a developmental anomaly in which normal bone marrow is replaced by fibro-osseous tissue.

Types:

• Monostatic: Single bone, can present at any age, but most commonly in the second decay. Most common bone involvement in descending order (ribs “most common”, proximal femur, Tibia, and humerus).

• Polyostatic: Multiple bone, usually presented by 10 years. Usually presented as unilateral involvement. Femur, pelvis and tibia are most common site of involvement. Skull and facial bone are commonly affected.

• Craniofacial fibrous dysplasia.

• Cherubism: Only mandible and maxilla.

McCune-Albright syndrome: It is a triad of polyostotic fibrous dysplasia, café-au-lait macules, and endocrine dysfunction. It is a nonhereditary, affects mainly female.

Clinical findings:

It could be incidental finding. The usual presentation is pain, swelling and leg length discrepancy.

Radiological finding:

Plain film: The lesion appears non-aggressive (no periosteal reaction, no cortical destruction, and no soft tissue mass).

It may be presented as focal enlargement of the bone or bubbly appearance.

It has ground glass matrix with narrow zone of transition usually and endosteal scalloping.

It may be present with deformity “Shepherd’s crook” of proximal femur or bowing, leg length discrepancy or pathological fractures.

CT scan: Well defined maybe sclerotic borders, ground glass matrix.

MRI scan:

T1 WI: Intermediate heterogeneous signal.

T2 WI: Low SI heterogeneous signal.

T1 C+ (Gd): Heterogeneous contrast enhancement.

Scintigraphy: Increased tracer uptake on Tc99 bone scans.

Complications:

• Pathological fractures.

• Deformity.

• Malignant transformation (rare) osteosarcoma, fibrosarcoma or chondrosarcoma.

FURTHER READING:

1. Lane F Donnelly. Fundamental of pediatric radiology. ISBN-13: 978-0721690612

2. Johan G Blickman, Bruce R Parker, Patrick D Barnes. Pediatric Radiology: The Requisites, 3e. ISBN-10: 0323031250