A confounding rib variation: bilateral symmetric aberrant posterior rib articulations and bridgings

Although mild bone angulation with osseous enlargement often suggests fractures with callus formation, in some cases the diagnosis is synchondrosis.

We present a rare variation of the chest wall in a 15-year-old male with a history of lymphoma. Bilateral multi-level posterior rib enlargements revealing mild ¹⁸F-fluorodeoxyglucose uptake were detected via positron-emission tomography/computed tomography. The variations were identified as healing fractures, although the more accurate diagnosis was determined to be multi-level posterior rib synchondroses with consecutive bridgings. Although variant bone anatomies are commonly seen in radiological practice, such multiple symmetrical posterior rib synchondroses associated with consecutive bridgings and articulations have not been clearly demonstrated before.

Awareness of such a rare combination of a well-known variation is crucial for radiologists to exclude malignancies, possibility of fracture and suspicion of child abuse.