Magnetic Resonance Imaging of Aneurysmal Bone Cyst WILLIAM D. ZIMMER, M.D.  Mayo Clinic Proceedings  Volume 59, Issue 9, Pages 633-636 (September 1984) DOI: 10.1016/S0025-6196(12)62416-1 Copyright © 1984 Mayo Foundation for Medical Education and Research Terms and Conditions

Fig. 1 Anteroposterior (A) and lateral(B) plain films of aneurysmal bone cyst. Margins of lesion are fairly well defined without sclerosis. Thick periosteal new bone is seen medially. Lesion is markedly expansile and extends into medial and posterior soft tissues. Thin, calcified rim is demonstrated around part of soft tissue mass. Mayo Clinic Proceedings 1984 59, 633-636DOI: (10.1016/S0025-6196(12)62416-1) Copyright © 1984 Mayo Foundation for Medical Education and Research Terms and Conditions

Fig. 2 Computed tomogram of aneurysmal bone cyst (correlates with Fig. 3) without contrast material at slice thickness of 1 cm, showing discrete sclerotic margination of lytic lesion from medullary canal. Thin rim of calcium surrounds soft tissue mass. Mass pushes neurovascular structures posteriorly but does not invade them. Mayo Clinic Proceedings 1984 59, 633-636DOI: (10.1016/S0025-6196(12)62416-1) Copyright © 1984 Mayo Foundation for Medical Education and Research Terms and Conditions

Fig. 3 MRI in axial plane through aneurysmal bone cyst; SE sequence with TR of 2,000 ms and TE of 40 ms (correlates with Fig. 2). Bulk of lesion is of high intensity. Of less intensity (in decreasing order) are subcutaneous fat, bone marrow, muscle, and bone cortex. Low-signal popliteal vessels are seen posterior and lateral to lesion. Lesion is surrounded by low-intensity rim due to fibrocartilage or bone; it corresponds to calcium seen on computed tomogram (Fig. 2). This rim sharply demarcates lesion from surrounding fat; this margin was not shown as completely on computed tomogram. Lesion is also well demarcated from normal medullary canal. Mayo Clinic Proceedings 1984 59, 633-636DOI: (10.1016/S0025-6196(12)62416-1) Copyright © 1984 Mayo Foundation for Medical Education and Research Terms and Conditions

Fig. 4 MRI (coronal slice); SE sequence with TR of 250 ms and TE of 40 ms (correlates with Fig. 1). Lesion extends to but not through epiphyseal plate. Mayo Clinic Proceedings 1984 59, 633-636DOI: (10.1016/S0025-6196(12)62416-1) Copyright © 1984 Mayo Foundation for Medical Education and Research Terms and Conditions

Fig. 5 Low-power photomicrograph illustrating typical appearance of aneurysmal bone cyst. Multinucleated giant cells lie within fibrous septae, which lack endothelial lining. (Hematoxylin and eosin; × 40.) Mayo Clinic Proceedings 1984 59, 633-636DOI: (10.1016/S0025-6196(12)62416-1) Copyright © 1984 Mayo Foundation for Medical Education and Research Terms and Conditions