Fusion of the ribs is one of the most frequent anomalies in rib pathologies. Anomalies of the ribs may be isolated or a component of a congenital syndrome or metabolic disease. It is usually asymptomatic and detected incidentally on a plain chest radiography. Presently described is a case of a patient with a rib fusion mimicking a cavitary lesion observed on a plain chest radiography. Rib anomalies, including rib fusion, are often undiagnosed during radiological evaluation; however, they may lead to unnecessary diagnostic tests and treatments. Thus, rib fusion should be considered in the differential diagnosis of cavitary lesions.