Elastofibroma Dorsi Incidentally Detected by 18F-FDG PET/CT Imaging

Abstract

Elastofibroma dorsi (ED) is a rare pseudotumor of the soft tissues that can also show 18F-fluorodeoxyglucose (F-18-FDG) uptake on positron emission tomography combined with computed tomography (PET/CT) imaging. The aim of this retrospectively study was to describe the metabolic characteristics of ED incidentally detected by F-18-FDG PET/CT imaging.

Between November 2009 and August 2013 at our institution, 10,350 consecutive PET/CT examinations were retrospectively investigated. In 176 of these patients, ED was recorded as an incidental finding. Fifty-five of 176 patients also had follow-up scans after chemoradiotherapy. A total of 231 scans with ED in 176 patients were identified. To determine the metabolic activity of ED, the maximum standardized uptake value (SUVmax) was calculated semiquantitatively. For measurement size of ED, the longest axis of transaxial CT images was used. Seven of the 176 patients underwent surgery due to suspected metastases and/or invasion of primary malignancy and/or symptoms or incidental during surgery.

The prevalence of ED in our series was 1.7 %. The lesions were located in the subscapular region in all patients, except in one case with a lesion in the infrascapular region. A total of 419 ED lesions in 231 scan of 176 patients were evaluated. Mean +/- A SD SUVmax and long axis values for these 419 lesions were 2.31 +/- A 0.61 (range 1.0-4.30) and 56.78 +/- A 17.01 mm (range 19-112 mm), respectively. Of these 176 patients, 141 (80.1 %) had bilateral lesions and 35 (19.9 %) had unilateral lesions. There were statistically significant differences in the SUVmax and long axis values between the right and left side in the bilateral lesions (p = 0.001). No significant differences in the SUVmax and long axis values of the lesion were found between pre- and posttreatment in the patients with follow-up scans.

Elastofibroma dorsi located in the scapular region is usually bilateral, asymmetric and with mild or moderate metabolic activity on PET/CT imaging. In addition, the metabolic activity and size of ED remained stable after chemoradiotherapy. Awareness of these metabolic characteristics of ED is important for preventing misinterpretation during F-18-FDG PET/CT studies.