Pathologic Fractures, secondary to metastatic prostate cancer

53-year-old male with unrelenting back pain and a history of metastatic prostate cancer. The sagittal T1-weighted image demonstrates extensive osseous metastatic disease to the lumbar spine, where the marrow signal is hypointense. The sagittal T2 and STIR-weighted images demonstrate significant edema within the sacrum, worse in the alar regions. The axial T1-weighted image through the sacral ala demonstrate metastatic deposits at S1, adjacent to the uppermost portions of the sacroiliac joints. On the axial fluid sensitive sequence, there are fluid filled fracture lines through the right and left sacral ala. The findings are compatible with bilateral sacral alar fractures in the setting of metastatic prostate cancer. Pathological fractures are fractures that occur in abnormal bone due to either malignant or non-malignant causes. Pathological fractures are concerning because they are associated with significant morbidity due to decreased mobility when the spine and pelvis are involved.