Differential X-Ray Diagnostics of Aneurysmal and Simple Bone Cyst

Background:

Improving the differential diagnostics of aneurysmal bone cyst using X-ray studies

Patients and Methods:

There were 50 patients (28 men, 22 women) aged from 13 to 52 with cystic bone formations in the study group. Radiological diagnoses included 24 patients with aneurysmal bone cyst and 26 with simple bone cyst. X-ray evaluation of following characteristics was done: location, size , texture, contours, bone shape, periosteaum reaction, and the presence of pathological fractures. To verify the diagnosis, all the patients were conducted MRI of the affected bones in the T1, T2 , STIR conditions in axial, coronary, and sagittal planes. Specific indices were calculated for aneurysmal bone cyst such radiological signs as texture, localization of the tumor, and bone deformity

Results:

The effect of long bones in the group is 72.5% (including 28.6% of aneurysmal bone cysts, 81.4% of simple bone cyst), flat bones were affected in 27.5% of cases (including 78.5% of aneurysmal bone cysts, 21.5% of simple bone cysts). In 45.5% of the cases aneurysmal bone cyst was located in the metaphysis of long bones, 38.5% in the pineal gland, and17.5% in the shaft. Simple bone cysts in 31.5% of the cases were located in the metaphysis, 28.5% in the epiphysis and 17% in the diaphysis. There was no significant difference between X-rays and MRI data concerning localization of revealed structures. The average diameter of aneurysmal bone cysts was 7.8 cm, and that of simple bone cysts was 6.2 cm. A chamber structure was revealed at 38.2% of patients, including 21.5% of aneurismal bone cysts, and 78.5% of simple bone cysts. The multi-chamber structure was observed in 61.8% of patients (79.5% of them had aneurysmal bone cyst, and 20.5% had simple bone cyst). In 52.2% of patients (78.6% of them had aneurysmal bone cysts, 21.4% had simple bone cysts) the contents of cysts on MRI was heterogeneous due to the presence of blood. In all patients, the lumen of cysts on radiographs was defined as a homogeneous area of enlightenment. Pathological fracture was detected in 12.4% of patients with aneurysmal bone cyst, and 21.4% of patients with simple bone cyst. The presence of sclerotic loops was revealed in 62.6% of patients ( aneurysmal bone cyst, 18.5%; simple bone cyst, 81.5%). Swelling of bone was observed in 78.2% of patients, including aneurysmal bone cyst in 58.5% and simple bone cyst in 41.5% of cases. There was periosteal reaction in the form of linear periostitis in 24.5% of patients with aneurysmal bone cyst. No changes in the periosteum were found in the patients with simple bone cyst. The percentages pertaining to indicators of specific structure, localization of new formation, and changes in the shape of bones for aneurysmal bone cysts were 81.8%, 63.2%, and 42.4%, respectively.

Conclusions:

According to our data, the structure of formation is the most specific out of all radiographic evidences. MRI is superior to X-ray in evaluation of structure bone cyst formation. It most accurately indicates the nature of their contents. Results of X-ray method and MRI regarding identification of location, size and contour of bone cyst, bone deformation, periosteal reaction, and the presence of pathologic fracture did not show significant difference.