[MR morphology of primary aneurysmal bone cysts: a retrospective analysis of 38 cases].

PURPOSE: To define MR imaging characteristics of primary aneurysmal bone cyst.

MATERIALS AND

METHODS

MR imaging studies of 38 patients with histologically proven primary aneurysmal bone cyst were reviewed with reference to morphological features, signal characteristics, and patterns of contrast-enhancement.

RESULT: Most lesions were well marginated towards bone and soft tissues (95%), either surrounded by a complete (84%) or incomplete (16%) rim of low signal intensity on images of all pulse sequences. Frequent features were polycyclic margins (84%), cortical expansion (87%), cystic spaces (100%), contrast-enhancing cyst walls (100%), internal septations (89%), fluid levels (71%) and diverticula-like projections of cyst walls (68%). Solid tissue components could be identified by MR imaging in all lesions which, on pathological examination, contained larger portions of solid material (18%). Edema of surrounding soft-tissues was observed in 29% of the cases.

CONCLUSIONS

Primary aneurysmal bone cysts demonstrate a relatively uniform MR imaging appearance, which reflects the patho-anatomic composition of the lesion.