A girl aged 5 years presented with a cough and difficulty breathing of one week’s duration. She had no known disease, and the physical examination was unremarkable. The posterior-anterior chest radiograph showed an abnormally oriented rib in the upper right side of the chest (Fig. 1). The patient underwent a low-dose CT scan of the chest without contrast for further evaluation. The CT scan revealed the presence of a bifid intrathoracic rib protruding into the lung parenchyma (Fig. 2, Movie). Since the patient’s symptoms were mild, conservative treatment was initiated and a follow-up visit scheduled.

Figure 1.

Anterior–posterior chest radiograph showing an abnormally oriented rib in the right side (arrowheads).

Figure 2.

(a) Axial and (b) coronal chest CT images evincing the intrathoracic rib (arrowheads). (c) Three-dimensional volume reconstruction chest CT image of the right lung demonstrates the parenchymal indentation of the intrathoracic rib (arrows).

An intrathoracic rib, also known as a thoracic rib or slipping rib syndrome, is an extremely rare anomaly of the chest wall in which a normal, supernumerary or bifid rib is located within the chest cavity.1 The clinical manifestations of intrathoracic rib can include sharp or dull pain, difficulty breathing or shortness of breath and a palpable lump or bulge near the involved rib.1 The management of this type of malformation typically involves a combination of conservative measures and, in severe cases, surgical intervention.2 A chest CT scan allows precise visualization of the tubular shape and curvature of the intrathoracic rib and can be used to guide surgery.1,2