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Age / Sex : 14 / F
14/F
C.C.: trauma (Click to enlarge)
1) What is your impression?
2) A first impression and three or less differential diagnoses are acceptable.
Courtesy : Young-sook Kim, MD
Chosun University College of Medicine
Diagnosis: fibrous dysplasia with pathologic Fx
Discussion
Findings:
1) Figure 1: - The femur AP & Lateral : fracture in the proximal shaft portion with osteolytic lesion
2) Figure 2 : Coronal MR Image - T2WI ; High SI lesion with low SI rim - Fat saturate T1WI ; Iso or slightly high SI lesion to surrounding muscle signal intensity
3) Figure 3 : Axial MR Image Proximal portion of fracture site - T1WI ; Low SI lesion with cortical thining - T2WI ; High SI lesion with cortical thining
Differential Diagnosis:
Fibrous Dysplasia, Unicarmeral bone cyst
Diagnosis: Fibrous Dysplasia with pathologic fracture
Discussion:
The common cause of the pathological fracture in children are simple bone cyst, nonossifying fibroma, fibrous dysplasia, aneurysmal bone cyst and osteosarcoma. The most common primary location are the proximal humerus and proximal femur. Fibrous dysplasia is relatively common benign skeletal disorder, typically encountered in adolescents and young adults. Rather than a true neoplasm, fibrous dysplasia a developmental anomaly in which the normal medullary space of the affected bone is replaced by fibroosseous tissue. The process may affect a single bone(monostoic FD) or many bones( polyostotic FD). Radiographs demonstrate intramedullary, well defined, sclerotic margined, expansile, ground glass patterned lytic lesion. The normal architecture of bone is altered and remodeled. Occasionally, there are small island of cartilage can under go calcification. MR findings are decreased signal intensity on T1WI and variable signal intensity in T2WI. This variable appearance on T2WI ranges from high signal intensity to intermediate or low signal intensity. Radiologic differential diagnoses include simple bone cyst, giant cell tumor, fibroxantoma, neurofibromatosis, hyperparathyroidism, enchondromatosis, eosionphilic granuloma, osteoblastoma, hemangioma, and meningioma. Monostotic FD may be indistinguishable from simple bone cyst. The finding of a thick peripheral rind surrounding the lesion favors the diagnosis of fibrous dysplasia over bone cyst. Bone scintigraphy is usually helpful in separating the two entities, which FD typically demonstrating marked radionuclide accumulation, which is nor seen in a cyst unless it has been complicated by pathologic fracture. If a pathologic fracture has occured, the radiography reveal a fallen fragment sign or fluid-fluid level in simple bone cyst.
References:
1. Ortiz EJ, Isler MH, Navia JE, Canosa R. Pathologic fractures in children. Clin Orthop Relat Res. 2005 Mar; (432); 116-126
2. Krandort MJ, Moser RP, Gilkey FW. Fibrous dysplasia. Radiographics 1990;10; 519-537
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