Presentation
Non-tender bony prominence on right anterolateral chest.
Patient Data
Soft tissue ultrasound corresponding to the site of the palpable bony protuberance confirms a bifid rib within the right anterolateral thoracic cage. The rib is easily followed along its course to bifurcate or fork at its sternal end. The exact rib may be difficult to confirm sonographically, especially in a pediatric patient, and dedicated chest and rib views can be utilized to confirm this sonographic finding and to exclude other occult pathology.
Sonographer: Ms Roekshana Nana
Annotated images outline the bifid right 4th rib and demonstrate the skeletal asymmetry when compared to the normal left ribs.
Chest x-ray confirms the bifid right-sided 4th rib. The thoracic skeleton is otherwise normal. There is a normal cardiomediastinal contour with no indirect features to suggest a congenital cardiac anomaly (such as truncus arteriosus or tetralogy of Fallot which are common associations). There are twelve pairs of ribs.
The zoomed, reverse window and annotated images demonstrate the bifid 4th right rib.
Case Discussion
A bifid rib is a congenital skeletal abnormality of the thoracic rib cage when the sternal end of a rib is cleaved into two. It is usually a unilateral finding with a right-sided and female predilection. An isolated bifid rib requires no further intervention. Bifid ribs can be associated with Gorlin-Gotz (a.k.a. basal cell nevus syndrome), a rare phakomatosis presenting with multiple odontogenic keratocysts, multiple basal cell carcinomas and other craniofacial, skeletal and neoplastic abnormalities.
As shown on the above chest x-ray, the bifid rib is barely discernable and may easily be missed on routine radiographs unless the rib asymmetry is identified.
Case courtesy of Dr Pearl GNM Quvane.