Rhomboid Fossa of the Clavicle

The rhomboid fossa is a normal concave lucent irregularity that may be seen along the inferomedial aspect of the clavicle. It is the insertion site of the costoclavicular ligament. The rhomboid fossa may be mistaken for an osteolytic lesion or apical pneumothorax.

References

Kumar R, Madewell JE, Swischuk LE, Lindell MM, David R. The clavicle: normal and abnormal. Radiographics. 1989 Jul;9(4):677-706.