대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Fibrous dysplasia of the rib

Radiologic Findings

PA chest radiograph shows a large mass originating from the right 5th rib. Unenhanced CT scan (CT1) shows a well-defined expansile bony mass with cortical expansion. However, there are multifocal areas of cortical
disruption along the tumoral margin. Enhanced CT scans (CT2 and CT3) show mild enhancement of the mass with multifocal areas of slightly low attenuation. All CT scans show intratumoral calcifications or bony fragments.

Brief Review

Well-circumscribed margin of the tumor with overlying cortical expansion favors benig rather than malignant bone tumor. However, there are multifocal areas of cortical disruption along the tumoral margin. This finding may suggest an aggressive nature of the tumor or malignancy. Fibrous dysplasia is usually a slowly progressive, benign disease that develops over several years and presents with deformity or mild symptoms. It is a benign disorder of bone that can cause cortical thinning as well as bony expansion. On conventional radiography, aggressive fibrous dysplasia may produce opacification and expansion of the underlying bone and apparent disruption of its wall with an associated soft tissue mass. According to Shapeero et al [1], computed tomography (CT) demonstrated voluminous heterogeneous masses with "ground glass appearance", calcifications, areas of enhancement, low attenuation, cystic areas, and a thinned, sometimes interrupted, cortical wall. Despite the aggressive clinical course, the CT findings of a "ground glass" mass with calcifications surrounded by cortical wall, even if incomplete, can suggest the diagnosis of aggressive fibrous dysplasia. There has been also a report of three cases of fibrous dysplasia with aggressive and potentially confusing feature [2]. According to Yao et al [2], well-defined cortical perforations without associated periosteal reaction were clearly seen on CT. Full-thickness cortical bony destruction can be seen in fibrous dysplasia. This finding, which may only be evident on cross-sectional imaging studies, should not by itself alter a diagnostic impression of fibrous dysplasia supported by other radiographic and clinical features.

References

1. Shapeero LG, Vanel D, Ackerman LV, et al. Aggressive fibrous dysplasia of the maxillary sinus. Skeletal Radiol 1993;22:563-568
2. Yao L, Eckardt JJ, Seeger LL. Fibrous dysplasia associated with cortical bony destruction: CT and MR findings. J Comput Assist Tomogr 1994;18:91-94

Keywords

Chest wall, Rib, Benign tumor,