Imaging Diagnosis of Thoracic Elastofibroma Dorsi.

Objective: Elastofibroma dorsi (ED) is an uncommon benign tumor that is commonly incidentally discovered on thoracic imaging and at times misinterpreted as a more aggressive lesion. The objective of the study is to characterize the typical cross-sectional imaging findings of elastofibroma dorsi and quantify the risk of masquerading malignancy.

Methods: Retrospective search of radiology and pathology reports over a 12-year period identified 409 cases of suspected ED. Pertinent imaging was reviewed with a focus on computed tomography (CT) and magnetic resonance imaging (MRI), specifically assessing lesion location, presence of interspersed fat, and appearances on follow-up.

Results: Typical imaging appearances of 310 ED, including 10% with pathologic confirmation, were that of a mass deep to the serratus anterior (98%) and near the scapular tip (98%). Intralesional interspersed fat was present in 87% of cases imaged with CT and in 90% of cases imaged with MRI. In the 43 cases imaged with both modalities, 8 (19%) did not have interspersed fat on CT, but 7 (88%) of these did have interspersed fat on MRI. Twelve tumors (benign and malignant) were included, of which only 17% were deep to serratus anterior and 25% were at the scapular tip, P = 0.0001 and P < 0.0001 versus ED. Only a single tumor contained interspersed fat, P < 0.001 versus ED, which had benign pathology on biopsy.

Conclusions: Elastofibroma dorsi can be diagnosed with a high degree of certainty in the presence of classic location and imaging characteristics, obviating the need for further imaging or biopsy.