Left inferior ramus lesion.IMAGE ACQUISITIONS: Noncontrast CT of the pelvis was performed with standard CT protocol. There is an irregular lucency measuring approximately 1.2 cm through the left inferior pubic ramus which demonstrates sclerotic margins and slight expansile remodeling however there is no associated soft tissue mass. There is no similar findings on the contralateral side. The remainder of the visualized osseous structures are within normal limits. The visualized lower lumbar spine and sacrum also are within normal limits. Sacroiliac joints are within normal limitsThe surrounding soft tissue structures including the musculature surrounding this lucency in the left inferior pubic ramus appears within normal limits. The edema seen on outside MRI study surrounding this lesion is not appreciated on CT examination which is expected.
Irregular lucency with sclerotic margins in the left inferior pubic ramus with no associated soft tissue mass is most compatible with a benign lesion. The location and imaging appearance of this finding is highly suggestive of the ischiopubic synchondrosis which represents a normal ossification process however given the patient is symptomatic, it has been described to have stress reaction or swelling of the synchondrosis. Alternatively, this could be a fracture however it is an atypical place. Much less likely and still benign in etiology, this could represent an atypical appearing eosinophilic granuloma.Given the findings are most likely secondary to a swollen ischiopubic synchondrosis, short-term follow-up CT examination in 3 to 6 months is recommended to evaluate for change or resolution of findings.