Evaluate bone lesion. ABC versus UBC. There is a fairly circumferentially expansile lesion within the proximal humerus extending from the proximal metaphysis to diaphysis over a 7 cm length. The lesion has slightly heterogeneous intermediate T1 signal and high T2 signal with a fluid-fluid level. There is no significant surrounding edema. There cortex appears discontinuous mid-lesion which likely reflects the non-displaced fracture seen on the prior radiograph. There is central low signal and rim enhancement on post-contrast imaging. The remaining bone marrow signal is within normal limits. The musculature and soft tissues appear normal.
Findings most likely represent a unicameral bone cyst in the proximal humerus given location, signal characteristics, and enhancement pattern. An aneurysmal bone cyst is considered less likely.