One of the complications of a simple bone cyst is fracture. The fracture is often transverse and one sign that is touted is the "fallen fragment sign", due to fragments of bone that are seen in the dependent portion on erect images (Fig. 1) - usually in the inferior aspect of the cyst. Even on MRI, which is performed in the supine position, bone fragments may be seen in the inferior aspect (Figs. 2, 3).
When the infection involves a dilated PC system, there is pyonephrosis, as in this patient with a calculus in the lower third with hydronephrosis. There is reduced function with enhancement of the walls of the pelvis and calyces (Fig. 1). A focal parenchymal lesion is also noted (Fig. 2).
This 30-years old patient had pain in the right lower jaw. He had been treated earlier for caries. An OPG showed an osteolytic lesion and the patient came for a dental CT, which showed a well-defined, odontogenic lesion, with its epicentre in relation to the root of the first molar tooth, but extending from the second premolar to the second molar (Figs. 1-4).
This 11-years old girl had left hip pain. The plain radiograph showed a mildly expansile osteolytic lesion with a narrow zone of transition in the distal neck (Fig. 1). A simple bone cyst was suspected and the CT (Fig. 2) and MRI (Figs. 3-5) confirmed this possibility.
In view of the age and location, the treating doctor decided to treat the patient conservatively and sent her for a CT-guided steroid injection. This was performed with CT fluroscopy control and after introducing a needle into the lesion (Fig. 6), a mixture of methylprednisolone and intravenous contrast was injected (Figs. 7, 8). Queried after a week, the patient confirmed relief from pain.