Presentation
Fall from a normal height dining chair, immediate upper arm pain and now not moving arm. Fracture?
Patient Data
A well circumscribed lucent bone lesion with a thin zone of transition is present in the proximal humeral diaphysis. There is bony expansion and cortical thinning.
A fracture is present at the medial margin and several bone fragments are present within the lesion. Some of these have 'fallen' to the distal aspect.
Case Discussion
This case shows classic appearances of a unicameral bone cyst with pathological fracture (resulting from a normal force on an abnormal bone) and fallen fragment sign.
These lesions can appear aggressive on MRI and XR is usually sufficient for a diagnosis.
This fracture may stimulate healing of the cyst by way of sclerosis.